A draft guide
to learning and teaching ichthyology
FishBase information system
This guide provides a structure and case study material for a
computer-based course in ichthyology for upper undergraduate and graduates
students in biology or environmental science.
The key resource made accessible through this guide is FishBase, a large
database on the biology of fish, available on CD-ROM (for the Windows operating
system) and on the Internet (www.fishbase.org/search.cfm).
Following brief introductions to ichthyology and to FishBase, and to the
use of the latter to teach the former, the key aspects of ichthyology are
presented in five chapters covering Evolution and classification; Morphology and
biodiversity; Reproduction; Physiology; and Fishes as part of ecosystems.
For each of these chapters, one or several ‘Exercises’ are presented
describing how the relevant topics are covered in FishBase and describing how to
access that information. ‘Tasks for the Student’ are provided, along with
Internet links to relevant sources other than FishBase.
It is anticipated that this guide will improve as our experience with
FishBase as a teaching tool improves. Thus, a final chapter describes how users
(both students and teachers) may contribute to the frequent updates that are
anticipated for this guide, and to completing the coverage by FishBase of the
biology of fishes.
use one to teach the other?
in a name?
Indo-Pacific shore fishes
shapes and sizes
Diversity of brain sizes
of growth and mortality
Diversity of habitats: inferences from occurrence records
of colors and sexual selection
Diversity of food
and feeding habits
and no worries
and parental investment
on the basic themes
food consumption from empirical models
as Part of Exploited Ecosystems
and trophic levels
Trophic levels and sizes of fish
description of food webs
A: Ichthyology resources on the net
Appendix B: fish-related web resources for UBC
Ichthyology, commonly defined as “the study of fish” or “that branch of zoology dealing with fish” has a long documented history, dating thousands of years back to the ancient Egyptians, Indians, Chinese, Greeks and Romans (Cuvier 1828).
This long, sustained interest in fish is due
to their double role as highly speciose denizens of a fascinating, yet alien
world, and as human food. It has generated, over the centuries, highly
heterogeneous information—mainly taxonomic, but also referring to
zoogeography, behavior, food, predators, environmental tolerances, etc.
This huge amount of information, embodied in a
widely scattered literature, has gradually forced ichthyologists to specialize,
and thus accounts on fish are now either global, but highly specialized (e.g.
Eschmeyer’s Catalog of fishes (1998)
or Pietsch and Grobecker’s Frogfishes of the world (1987) to name two outstanding
representatives), or local and deep (e.g. Fryer and Iles’ Cichlid Fishes of the Great Lakes of Africa (1972) or Groot and
Margolis’ Pacific Salmon Life Histories
Thus, with a few exceptions such as the
massive Diversity of fishes (Helfman
et al. 1997), texts are lacking which bring together, on a global basis, all
aspects of ichthyology, such that they can be used for a specialized course,
and/or independent learning.
FishBase is an information system available in
the form of CD-ROMS and on-line, at www.fishbase.org/search.cfm,
covering all fishes of the world in a fashion that is both global and deep.
FishBase 99, whose accompanying book is available both in English and French,
covers over 23,000 species of fish, i.e. most of the 25,000 extant species, and
addresses the needs of a vast array of potential users, ranging from fisheries
managers to biology teachers. The features of FishBase that enable it to meet
such a wide range of needs reside in its architecture, which makes extensive use
of modern relational database techniques.
Other features of FishBase are:
information on a given species in the database is accessible through a unique
scientific or common name;
use of multiple choice field structures standardized qualitative information;
fields record quantitative information that has been previously standardized;
cross-relationships between data tables enable previously unknown relationships
to be discovered; and
databases provided by colleagues and linked to FishBase proper, contribute to
making the combined package the most comprehensive data source of its kind.
For teachers of aquatic biology, or of specialized ichthyology courses, the uses of FishBase will range from practical solutions to theoretical issues:
is directly useable as data source (i.e., as an electronic encyclopedia on
fish), thus complementing classical sources of information on fish, e.g., the Zoological
Record or Aquatic
Science and Fisheries Abstracts,
and helping overcome the lack of scientific literature, especially in developing
pictures in FishBase can be used, just as those in taxonomic books, to provide
students with a visual impression of the morphological and color diversity of
fish, and/or of specific features of various groups;
will be able to assess the state of knowledge on various groups of fish, and
thus obtain some guidance in identifying worthwhile projects; and
synoptical view that FishBase produces by assembling and structuring all
available information on one species will help students to obtain material for
study (see above) and, perhaps more importantly, to develop a sense of how
scattered bits of knowledge can be used to ‘reconstruct’ species, and to
show how these fit into their environments, thus encouraging a ‘holistic
view’, as now required for most of what we do in the biological sciences.
Thus, aof lectures on ichthyology may be conceived, based on the following elements:
FishBase pictures through an introductory lecture, to highlight the diversity
and colorfulness of fish and similarity of external morphology in related groups
(this hopefully would serve to generate interest in the course as a whole, and
introduce fish classification);
the early classification schemes in Cuvier (1828) with a recent one, e.g., that
in the Catalog of fishes (Eschmeyer 1998), ‘hosted’ by FishBase and largely
identical with the widely used classification in Nelson (1994);
the species concept and its requirements (a formal description with figures, a
binomen, a holotype,
a type locality, etc.) and implications (synonymies, sister species, etc.),
using FishBase as source of examples, and its Glossary for definition of terms;
the characteristics (meristics,
through which fish species are usually defined and hence identified, and compare
identification through keys with computer-based identification using the
appropriate FishBase routine (see ‘Quick Identification’);
museum and other occurrence records, as included in FishBase, can be used to
define distribution ranges and habitats, which can then be used for ecological
the latitudinal ranges of fish species can be used to test various hypotheses,
e.g., on the relationship between fish biodiversity and shelf area (for marine
species) or land area (for freshwater species);
and illustrate various life history strategies, and analyze their frequency
distribution throughout the world. Show, e.g., that salmon-type anadromy
is extremely rare in subtropical or tropical species (it is well documented only
in hilsa, Tenualosa
ilisha, ranging from Iraq to Myanmar). Show
how students can identify the relative frequencies of different strategies and
draw inferences from these;
student select a species, print out the relevant FishBase synopsis and
complement it based on a literature review (and send the result to the FishBase
let students derive quantitative relationships between different expressions of
fish physiology (e.g., respiration, growth) and temperature (and hence latitude)
and identify modifying factors (salinity, gill size, food type, etc.).
In the context of higher education, FishBase
may also serve as background for Bachelor’s or Master’s theses wherein an
area of ichthyology not presently or suitably covered by the tables in the
latest version of FishBase would be ‘broken up’ into choice, numeric and
text fields, entered and then analyzed on a comparative basis.
There are different ways in which objects can be classified and the human mind is very good at generating criteria for classification. This is why the following list, assembled by the Argentinean author Jorge Luis Borges, and purportedly extracted from an ancient Chinese encyclopedia (Lakoff 1987), strikes us as funny:
“…it is written that animals are divided into:
that belong to the Emperor;
that are trained;
that are included in this classification;
that tremble as if they were mad;
drawn with a very fine camel’s hair brush;
that have just broken a flower vase;
that resemble flies from a distance.”
The two major criteria that are used to classify things (neither met by
Borges’ list), are utility or affinity:
classifications whose objects are easy to
find. An example of such a classification would be a dictionary, whose
entries are arranged alphabetically;
on the other hand generates classification wherein adjacent objects s are
straightforward to compare (because
adjacent entries share important features).
In the European middle ages, animal books (‘Bestiarum’) were usually ordered alphabetically. However, such
ordering eventually struck people as odd, especially as people realized, in the
course of long debates on ‘universals’ (on whether names are ‘natural’
attributes of things, or not), that names are arbitrary labels.
Thus, authors gradually began seeking for natural classifications,
wherein organisms are ordered by affinities, these affinities being initially
conceived as reflective of the general rules which god used when creating these
The work of Linnaeus, whose Systema
Naturae, the tenth edition of which in 1758 still marks the beginning of
zoological nomenclature, is an example of such attempts to identify the
underlying affinities among plants and animals. The resulting ‘natural’
classifications have started to make sense, however, only since Darwin, in The
Origin of Species (1859), provided a rationale for affinities, that is,
shared ancestry. Darwin not only provided a basis for the affinities between
organisms, however. He also provided a mechanism by which new species and higher
taxa emerged out of common ancestors. This mechanism he called natural
Natural selection is the core of Charles Darwin’s work and is best
defined in his own terms: “many of every
species are destroyed either in egg or [young or mature (the former state the
more common)]. In the course of thousand generations infinitesimally small
differences must inevitably tell; when unusually cold winter, or hot or dry
summer comes, then out of the whole body of individuals of any species, if there
be the smallest differences in their structure, habits, instincts [senses],
health, etc., <it> will on an average tell; as conditions change a rather
larger proportion will be preserved: so if the chief check to increase falls on
seeds or eggs, so will, in the course of 1,000 generations, or ten thousand,
those seeds (like one with down to fly) which fly furthest and get scattered
most ultimately rear most plants, and such small differences tend to be
hereditary like shades of expression in human countenance. (Darwin 1842)
Natural selection, thus, consists of three elements:
usually produce far more progeny than their habitat can accommodate;
member of the progeny differs in some inheritable
attributes or properties;
a tendency for those progeny with attributes or properties that are more
suitable for the habitat in question to suffer a lower rate of mortality and to
reproduce better than their siblings.
These three features jointly cause animals and plants to try to track fluctuation of the environment. In this process, and in conjunction with other mechanisms such as the ‘founder effect’ and the effect of neutral selection, isolated populations can become so different from a mother species that they will not be able to mate if the barrier that once separated them disappears.
Species are “groups of actually (or potentially) interbreeding natural populations which are reproductively isolated from other such groups” (Mayr 1942, p. 120).
Since species are the basic rank of biological nomenclature, naming
species is very important and we now follow for this a model proposed by
Linnaeus, (see above), wherein the species is defined by a so-called binomen
consisting of a unique genus name, always starting with a capital letter, and a species
, which is never capitalized; both are written in italics font. With regard to
the capitalization rule, simply recall that the binomen is the short version of
an earlier mode of description wherein a whole paragraph was used to describe,
and thereby define, a species. The binomen, thus, was the start of a sentence.
An important addition to a species name is the name of the author who
first described that species and the date of that description; as in, for
example, the Linnaean species Salmo
trutta Linnaeus, 1758. At times you will
encounter a species, e.g. Oncorhynchus
mykiss, with an author’s name and date in
brackets, e.g. (Walbaum, 1792). In this case, it means that the species whose
epithet is mykiss was originally
described as a memeber of another genus, in this case Salmo, and due to better understanding of its relationships with
other trouts, was subsequently moved into the genus Oncorhynchus which it
is now a member.
Another rule important to animal species names are that the genus part
of the name must be unique to the animal kingdom. From the year 2000 on, it must
also be unique among all organisms. Thus, when a generic name is coined, the
author must verify that this name has never been used by any other zoologist,
and, from 2000 on, by any botanist, bacteriologist, etc. The apparently daunting
task is not impossible, however, as global catalogues of organism names are now
being created; the most important of these is the Species 2000 catalogue (see www.sp2000.org).
Given the mechanism of natural selection, every fish population
can be conceived as being a potential new species. All one needs to imagine is
that populations become isolated from others long enough for their members to
lose the ability to mate with those of other populations. However, as long as
some members of each population continue to mate with members of other
populations of the same species, a mating barrier will not emerge (only a small
gene flow is required to prevent the emergence of a mating barrier). Thus
populations, though it might be easy to define them in terms of attributes such
as number of scales or spines or body proportions, should not be given full
taxonomic status because (contrary to species) they usually do not maintain
themselves over a long period. Not having taxonomic status also means they
should not have formal names, such as the trinomen
that are still frequently used today, e.g. Oreochromis
The third part of the trinomen refers to a subspecies, which is, in fact, a
population, or, to use a term much used in earlier times, a ‘race’.
Species differ as to the extent of their diversity. Some species consist of a single population of a few individuals — these are often endangered species. Others have wide ranges and a rich structure of populations – the situation which tempted authors to define subspecies as populations at opposite ends of a geographical range often differ in several characters. However, its is usually not objectively defined within-species diversity which has motivated authors to define subspecies, but national or local research traditions, and the resources available for taxonomy. Thus, Berg (1965) established numerous subspecies and even lower taxa for the fishes of adjacent lakes and rivers of the former Soviet Union, while subspecies are rarely proposed by taxonomists working on the many coral reef species of the Indo-Pacific, although their distribution spans thousands of kilometers, and detailed studies may justify this (at least if one believes in subspecies).
of fish are what most people know about most fish. Thus, capturing the common
names of fish in various languages captures most of what people who speak these
languages know about fish. For this reason, FishBase includes over 90,000 names
of fish in over 100 languages, ranging from widespread languages such as English
or Spanish, to languages spoken by few speakers, such as Haida in Haida Gwaii,
British Columbia. Anthropologists, notably Berlin (1965), have established that
essentially all ethnic groups in the world spontaneously differentiate a similar
number (about 500) of ‘kinds’ of organisms, the kinds roughly corresponding
to genera, with important species being named, as well as some of their life
The sounds in fish names also generate interesting patterns. Thus, small
fishes (i.e., fishes with small values of Lmax)
tend to have names containing high pitch sound such as ‘i’ or ‘ee’,
while large fish tend to have names with lower pitch sounds, such as ‘a’, or
‘aa’ (Berlin 1992; Palomares et al. 1999).
|Task for the Student:
Classification related topics covered in FishBase:
The diversity of fish is larger than for any other vertebrate group. Not
only are there more species of fish (25,000) than of all other vertebrates
together, but also the range of body shapes and sizes of fish is larger than for
mammals, birds or reptiles. Consequently, the range of habitat occupied is
larger as well.
The triangle formed by Indonesia, the Philippines and New Guinea,
collectively referred to as the ‘East Indies’, form the center of marine
fish biodiversity in the Indo-Pacific, with about 2,800 species naturally
occurring there. These numbers drop with distance from this center to about 500
species in Hawaii and 120 species in the Easter Islands. The number of endemic
species, i.e., fishes that do not occur outside a given area, increases with
distance from the center, supporting one hypothesis that species evolved in the
outer region and accumulated in the center. Another hypothesis holds that
species evolved in the rich and stable habitats of the East Indies and were
carried to the periphery by currents. Randall gives 5 explanations for fish
biodiversity in the Indo-Pacific:
· Sea surface temperatures in the East Indies were more stable during the glacial periods and thus extinction rates were lower than in the periphery;
area in the East Indies is much longer than that of the periphery, again making
extinctions less likely;
of shore fishes to remote islands occurs during the planktonic larval phase
which lasts from several days to several weeks. However, the larval phase of
many species is not long enough for long stretches of open ocean water, thus
restricting their distribution;
current patterns support dispersal of fish larvae from the area as well as
convergence of larvae of species that have evolved in the periphery towards the
the last 700,000 years, there have been at least 3 ice age events that reduced
the water level in the East Indies and separated populations long enough to
become different species.
|Task for the Student:
Biodiversity related topics in FishBase:
The shapes of fish are also extremely diverse, and include – besides
the torpedo shape perceived as ‘typical’ for fishes and termed
‘fusiform’– shapes ranging from the serpentine (in the Anguilliformes
and other orders) to the avian (in ‘flying
fishes’), with Latimera
limbs resembling, but not being used as, those of land-based tetrapods.
Shape and other morphological features are the key characteristics used
to date for classifying fishes, and hence understanding their classification
requires a basic overview of the basic shapes of fishes, as can be obtained from
the outline drawings included, for each of the existing 500 fish families.
Size is the most important attribute of individual organisms; it
determines what can be their food, and the extent to which they can be the prey
of other organisms. Size also determines how much food an animal requires to
eat, how fast it can swim, and to a large extent, where it can live.
The maximum size of fish can range from one centimeter in Philippine
e.g., Pandaka pygmea to 13-15 meters in the Whale
shark, Rhincodon typus. This diversity of
size allowed widely different environments to be colonized, ranging from
temporary puddles to the central gyres of the open ocean. However, colonizing
these environments required other adaptations, involving growth and mortality
rates, and their various correlates, discussed below.
The brain size per body weight of adult animals is related to the
sensory and behavioral capabilities of the respective species. For example,
fishes with well-developed electrosensing capabilities are known to have large
brains. The brain is the organ with the highest energy and oxygen demand, and
thus, fishes as well as other animals have evolved brain sizes that are neither
too small nor too large respective to the niches they occupy in nature.
|Task for the Student:
Brain size related topics covered in FishBase:
In spite of this wide diversity of fish sizes, clear patterns do emerge:
tropical fish tend to be smaller and faster-growing than their cold-water
counterparts and their natural mortality tends to be higher. This is due to high
temperature elevating the metabolic rates of tropical fish relative to their
Correspondingly, the natural mortalities experienced by fish, which are
a function of their sizes, range from values which exterminate an entire cohort
in a few months, e.g., the round
to 50 and more years in the lake
and 150 years in the orange
roughy. These enormous differences in life span
allow fish to respond differently to habitat variations. Small, short-lived fish
track such variations, for example, when growing up in temporary puddles and
laying desiccation-proof eggs before they dry up, thus being able to live
through dry periods or produce a successful cohort every 1-3 years or so (as may
happen in such long-lived fish as cod).
|Task for the Student:
Size, growth and mortality related topics covered in FishBase:
Fish inhabit more diverse habitats than any other group of vertebrates,
ranging from Himalayan or Andean brooks at 4000 meters to abyssal depth at 10
kilometers, spanning an extremely high range of pressures. The range of
temperatures that can be tolerated is also very large, from minus 2oC
as tolerated by the Antarctic fish, Pagothenia
borchgrevinki (which sport anti-freeze substances in their blood; see
Eastman and Devries 1985); to up to 40o C for Oreochromis
which lives at the edge of a hot spring in Lake Nakuru in Kenya. (This does not
consider the temperature tolerance of deep-sea vent fishes, which have not yet
been studied in detail).
Because fish occur only in habitats which they can tolerate, and tend to
be abundant in those habitats to which they are best adapted, occurrence records
kept by museums can be used to reconstruct the habitat preferences of fishes
whose ecology is otherwise unknown. Such records have been named bioquads
because they refer to biodiversity and consist of four key elements: (a) the
name of the organism; (b) the place where it was caught; (c) the source or
person who sampled or identified it; and (d) the date. FishBase makes wide use
of bioquads for documenting the distribution of fish and this can be emulated by
ichthyology students who may assemble bioquads from FishBase and other sources,
notably the Internet. (see Appendix
for sources of bioquads).
|Task for the Student:
Distribution and occurrence related topics covered in FishBase:
Fish are beautiful; they have beautiful colors and fascinating body
shapes, one of the reasons why people keep them in aquaria. Color patterns in
fish have been long misunderstood. Pre-Darwinian authors thought that god had
given fish such marvelous colors so that predators would find it easier to see
and catch them. We know, since Darwin, that such coloring, if it serves any
function at all, must benefit directly the ones who sport it and not their
predators as is obvious in the many color patterns that camouflage the owner, or
confuse predators, by, e.g., displaying large eyes in the wrong places. Darwin
also proposed a reason why non-camouflaging striking coloring should exist, and
that is sexual
Essentially, the males entice the females to choose them by displaying
nicer colors than other males; they compete in terms of their ‘beauty’, this
being related to good genes (remember Darwin did not know of genes and that part
of his theory was very hard on him). Recently, the Zahavi’s have complemented
Darwin’s version of sexual selection through a new concept, the handicap
principle, which takes into account that the colors and other adornments
which males use to entice females to choose them are costly to produce (Zahavi
and Zahavi 1997). Hence, the color and other adornments represent a handicap and
the males capable of displaying these attributes thus must have really good
genes for life-supporting traits. We may call this ‘truth in advertisement.’
The idea is that sporting highly symmetrical patterns, as, for example,
imperator, implies that the fish in question
had a harmonious development since development problems, due to genetic
problems, parasites or disease (also indicative of ‘bad genes’) would always
lead to asymmetries. Also, for colors that do not necessarily camouflage the
fish, sporting them indicates that the fish in question has been able to evade
predators. Some fish imitate the color patterns of other species to fool prey or
|Task for the Student:
Morphology related topics covered in FishBase:
Given the diversity of their sizes and habitats it is obvious that fish
should also have a wide diversity of food and feeding habits. Thus fish range
from feeding on microscopic phyto- and zooplankton to engulfing entire adult
fishes, such as is done by Whale
sharks or gulpers,
respectively. Attempts to link fish to their ecosystems have led to a huge
literature on their food and feeding habits. Unfortunately, some of this is
useless because it is reported in the wrong units, i.e., frequency of occurrence
of certain items in a number of stomachs sampled. Still, there are enough
studies in which the proper units have been used (percent contribution in
weight, energy or volume to total stomach contents) for a clear idea to emerge
of what fish generally eat in their typical habitat. Given knowledge of the
of their diet items, the trophic level of fish whose stomach content has been
studied can thus be computed, which allows evaluation of the position the
consumers occupy in the food web.
Hierarchy of food items, simplified from the FishBase table used to compute trophic levels (TL) from diet composition data. Therein, the TL of a consumer is 1 + (mean TL of the prey items).
|blue-green algae; dinoflagellates; diatoms; green
algae; other phytoplankton
|other plants||benthic algae/weeds; periphyton; terrestrial plants
|cnidarians||hard corals and other polyps||1.0|
|Polychaetes; other annelids; non-annelids
|chitons; bivalves; gastropods; octopi;, other
isopods; amphipods; other small forms
|shrimps; lobsters; crabs stomatopod; other large
stars/brittle stars; sea urchins; sea cucumbers; etc
|other benthic inverts||Other benthic invertebrates
cladocerans; mysids; euphausiids; etc.
fish and small sharks or rays
|Salamanders/newts; toads/frogs; turtles and other reptiles||1.0|
|sea and shore birds
|Small cetaceans and pinnipeds
in FishBase, these food items have distinct trophic levels (and
associated standard errors), not presented here.
|Task for the Student:
Food and feeding habits related topics covered in FishBase:
Fish usually reproduce when they have reached about half of the maximum
size they are likely to reach (Lmax). The size at which maturity is
first reached is called Lm and the fraction Lm/Lmax,
tends to be higher in small than in large fish. Thus, a goby with Lmax=10
cm will have a value of Lm = 7 cm, while in a Basking
shark with Lmax » 10 m, Lm will be about 4 m. Given
that fish of different sizes have different growth rates, their different Lm
values imply very different ages
at first maturity
Fish differ from most other vertebrates in that for most species, parental care is very limited or non-existent. The typical bony fish produces a large number of small eggs which hatch and become part of the phytoplankton, and which must beware of their parent (or their congeners) if these are zooplankton feeders.
The high fecundity of bony fish has led many to believe that they can be exploited very strongly, i.e., that there will always be some recruits even if the parental stock is much reduced. This is called the ‘million egg fallacy’ and it has caused untold damage to fisheries, especially cod fisheries. Still, it is useful to know the relationship between numbers of eggs spawned and the weight of the mothers.
|Task for the Student:
Reproductive load related topics covered in FishBase:
There are many fish which give birth to live young or which construct nests for their eggs, or which practice buccal incubation, e.g., in the Nile tilapia (see also Fish Quiz link in Exercise 7). Some other fish, notably the cartilaginous sharks and rays, give birth to fully-formed pups or produce very large eggs from which fully-formed young are hatched.
|Task for the Student:
Reproductive strategies (spawning behavior) related topics covered in FishBase:
As noted by Darwin, fish are extremely labile in their sex
determination, i.e., there are lots of fish which change sex, at least, far more
than in other vertebrate classes (e.g., wrasses, parrot fishes, groupers). These
are called hermaphrodites.
In some fishes the different life (and sex) stages differ so much in color
and/or form that they were originally described as different species. Fish also
give us neat examples of parasitic males, and other aberrant (?) behaviors.
|Task for the Student:
Reproductive strategies (sex change) related topics covered in FishBase:
The basic building blocks of fish bodies are proteins. Proteins have structure at several levels. The primary structure is determined by a sequence of the component amino acids, themselves with a structure determined by their sequence of atoms of carbon, hydrogen, etc. The secondary structure of most protein is a primary coil, similar to a braid. A third-level structure can emerge when the braids fold onto themselves, with various loops weakly connected by hydrogen bonds. It is this tertiary structure which determines the external shape of a protein, e.g. of an enzyme and hence how it will lock into ‘receptors’, often other molecules on the surface of cells.
Thermal noise is ubiquitous above absolute zero (0 Kelvin) and one of
its effects is to destroy the tertiary structure of protein, thus rendering it
ineffective. As a result, animals must break down such denatured molecules into
their constituent parts and re-synthesize them. This is the reason why it costs
energy to maintain a living body, even when it ‘does’ nothing, nor grows. In
mammals and birds, which maintain more or less constant internal body
temperatures, enzyme systems are geared such that the rate of synthesis matches
a certain level of thermal noise, i.e. that which occurs at 37 to 38 degrees
temperature. In fish, which except for large scombroids and some large sharks,
cannot maintain a constant body temperature, different external temperatures
thus imply different levels of thermal noise and hence rates of protein
denaturation. Thus, metabolic rate must vary with temperature and it does so
essentially in function of the need to re-synthesize protein.
However, it must be understood that the oxygen consumed by a fish is not its oxygen demand but the oxygen supplied
to it via its gills, i.e., the fish would use more oxygen if it could get it.
Hence, the amount of oxygen consumed by a fish is an imperfect measure of its
real ‘need’ for oxygen. Gill size grows in proportion to a power of body
weight that is less than one, i.e., the bigger fish of a given species become,
the smaller the gill area per body weight becomes. Hence, big fish, given a
certain level of activity, will tend to run out of oxygen faster than small fish
of the same species, other things being equal.
Ten species in FishBase with growth parameters, at least one length-weight relationship and three records each of gill area and oxygen consumption per unit body weight.
Salmo trutta trutta
Carassius auratus auratus
Cyprinus carpio carpio
|Task for the Student:
Metabolism related topics covered in FishBase:
Like other heterotrophic organisms, fish need food to survive and grow. Within ecosystems, trophic (feeding) relationships and energy flows largely define the function of various species. There are two ways of presenting species-specific consumption:
individual level, i.e., as the consumption of a particular food type by a fish
of a certain size, in the form of a daily ration (Rd); or
population level, i.e., as the consumption (Q) by an age-structured population
of weight (B), in the form of population-weighted consumption per unit biomass
There are a number of methods that can be used to estimate the daily ration of fish: studying the changes in stomach content in the course of a day, direct observation of captive fish, etc. One of these techniques is to infer ration from daily oxygen consumption, which is justified since the oxygen consumed is ultimately combined with the food consumed to generate ATP (adenosine triphosphate, the substance used to fuel internal metabolism). This is illustrated through an example for red piranha, Pygocentrus nattereri, adapted from Pauly (1994):
Data were analyzed using a multiple (log) linear regression which
yielded, for prediction of the metabolic rate (C, in mg02 · h-1)
in small Pygocentrus nattereri, the
C = 0.387 · W0.539· O21.13, … 1)
where W is the live weight of the fish in g, and O2 is the oxygen content of the water, in mg 1-1. The overall fit is good (R = 0.950); the standard errors of the exponents are 0.163 and 0.205, respectively, for 4 degrees of freedom. Given the small range of weights considered here, the relatively large standard errors about the estimates, and the low number of degrees of freedom, it would not be appropriate to assume that the slope linking O2 consumption and body weight is, in P. nattereri, significantly different from that proposed by Winberg (1960) for most fishes larger than guppies, i.e., 0.7 - 0.8. This implies that the equation above can be used only for a small range of weights, here 20 to 160 g.
For a 100 g fish in water with 6 mg O21-1, the
equation above predicts an O2 consumption of 35 mg·h-1,
i.e., 841 mgO2 ·day-1. An estimate of daily energy
consumption (Q) can be obtained from this using the approach of Wakeman et al.
Rd = (DW + RESP)/0.75, … 2)
where Rd is the ration, i.e., daily energy consumption in kcal, DW the energy content of the (daily) growth increment, and RESP is the oxygen consumption.
The first derivative (i.e. growth rate) of the von Bertalanffy equation
in terms of wet weight is
dw/dt = 3KW ((W¥/W)1/b-1) … 3).
This, solved for W¥ = 756 g, K = 0.893/365 = 0.00245 day-1, and b = 3, gives for a 100 g fish a daily growth increment of 0.706 g, corresponding to 0.706 kcal if the calorific value of fish wet weight is set equal to unity (Brett & Blackburn 1978). The available information on body composition of red piranha flesh (Junk 1976, in Smith 1979) is 8.2 % fat, 15.0 % protein, and 4.4 % ash, not very different from values reported from other fishes (Bykov 1983). Thus, if an oxycaloric equivalent of 0.00325 kcal·mg-1 O2 is assumed, as in other fishes (Elliot and Davidson 1975), the above estimate of 841 mg O2 day-1 becomes 2.733 kcal day-1. Thus,
Rd = 0.706 + 2.733/0.75 … 4)
or 4.585 kcal day-1 for a 100 g piranha. Food conversion efficiency (K1 = (dw/dt)/ Rd ; Ivlev 1966) would then be K1 = 0.154.
|Task for the Student:
Ration related topics covered in FishBase:
The method outlined above to deal with the ration of fishes lead to
point estimates, pertaining to a single size or age (group). A fish population
consists, however, of different size (age) groups, with small sizes and ages
being far more abundant than large sizes and ages. Thus, drawing inferences from
one (or several) ration estimate(s) pertaining to a given size (range) of fish,
to a population containing a multitude of size groups, requires a knowledge of
the size (age) structure of the population. An approach for performing this
inference is given in FishBase.
A large number of such inferences, from ration to
population weighted food consumption estimates (Q/B), have been performed in
recent years, notably Palomares and Pauly (1998). These estimates of Q/B can be
used in the context of empirical models to predict Q/B from other,
easy-to-estimate parameters. One such equation is
log Q/B = 7.964 – 0.204logW¥ – 1.965T’ + 0.083A + 0.532h + 0.398d … 5)
where Q/B is the food consumption, W¥ is the asymptotic weight in grams, T’= 1000/(°C+273.15), A is the aspect ratio of the caudal fin = h2/s, h=1 and d=0 for herbivores, h=0 and d=1 for detritivores, and h=0 and d=0 for carnivores.
Here, one key input is the aspect ratio of the caudal fin defined as in Figure 1
. Fish with tails with high aspect ratio consume more food than fish with
low aspect ratio tails, other things being equal. Needless to say, equation (5)
above cannot be used for fish (e.g. eels) which do not use their caudal fin as
their main propulsive organ. Other approaches can be used in such cases.
|Task for the Student:
Food consumption related topics covered in FishBase:
Fish populations do not live by themselves. Rather, they are embedded in
ecosystems where they perform their roles as consumers and prey of other
organisms, including larger fishes.
The role of fishes within ecosystems is largely a function of their size: small fish are more likely to have a vast array of predators than very large ones. On the other hand, various anatomical and physiological adaptations may lead to dietary specialization, enabling different fish species to function as herbivores, with a trophic level of 2.0, or as carnivores, with trophic levels typically ranging from 3.0 to about 4.5.
Moreover, trophic levels change during ontogeny
of fishes. Larvae, which usually feed on herbivorous zooplankton (TL= 2.0)
consequently have a trophic level of about 3.0. Subsequent growth enables the
juveniles to consume larger, predatory zooplankton and small fishes or benthic
invertebrates; this leads to an increase in trophic level, often culminating in
values around 4.5 in purely piscivorous, large fishes.
For formal descriptions of the role of fish in ecosystems and their
responses to changes in fishing, and other changes, see the Ecopath modeling
There is a strong link between Ecopath and FishBase, i.e., FishBase has
a special routine to assemble and print out information on the fish of a given
area or ecosystem, such that ecosystem models can be straightforwardly
|Task for the Student:
Food web related topics covered in FishBase:
The FishBase project is a large, international, non-profit venture which
started in 1989 and whose latest product, FishBase 99 (Froese and Pauly 1999)
covers all the fish in the world - at least in terms of nomenclature. In terms
of biology and ecology the coverage is, however, rather spotty and it is
paradoxically in the well-studied temperate areas that the coverage is most
incomplete, at least relative to the available literature. The reason for this
is that FishBase was funded by the European Commission to cover countries in
Africa, the Caribbean and the Pacific (‘ACP’) that are associated with the
For FishBase to realize its potential as the integrated, computerized
system of fish most useful to the global ichthyological community, it requires
input from users, including students. Thus you are encouraged to contribute to
FishBase, notably by sending reprints or photocopies of material used for your
analyses, as well as other information which you think should be incorporated
(with complete sources!). You are also welcome to submit photos or slides whose
originals would be returned to you after they have been scanned. See ‘How to
become a collaborator and why’ for details on the manners in which such
contributions are acknowledged; also note that you retain all rights to any
We wish to thank Ms. Donna Shanley, for creating a first workable draft out of a jumble of text notes, references and Internet URLs. Without her dedication and skill, the making of this guide would have continued to be postponed forever.
Berg, L.S. 1965. Freshwater fishes of the
U.S.S.R. and adjacent countries. In 3 Vol., 4th edition. Israel Program for
Scientific Translations Ltd., Jerusalem. [Original Russian version published in
Berlin, B. 1992. Ethnobiological
classification. Princeton Univ. Press, New Jersey. 335 p.
Bykov, V.P. 1983. Marine fishes: chemical
composition and processing properties. Amerind Publishing Co., New Delhi. 322 p.
Brett, J.R. & J.M. Blackburn. 1978.
Metabolic rate and energy expenditure of the spiny dogfish, Squalus
acanthias. J. Fish. Res. Board Can. 35: 816-821.
Cuvier, G. 1828. Historical portrait of the
progress of ichthyology, from its origin to our own time. Translated by A.J.
Simpson and edited by T.W. Pietsch (1995). The Johns Hopkins University Press,
Baltimore. 366 p.
Darwin, C. 1842. The Essay of 1842 p. 1-53 In:
F. Darwin (ed.). The Foundation of The Origins of Species: two essays written in
1842 and 1844. Cambridge, 1909. [Vol. 10 of ‘The Works of Charles Darwin’.
Pickering & Chatto, London, 199 p.]
Eastman, J.T. and A.L. Devries. 1985.
Adaptations for cryopelagic life in the Antarctic notothenioid fish Pagothenia
borchgrevinki. Polar Biol. 4:45-52.
J.M. and W. Davidson. 1975. Energy equivalents of oxygen consumption in animal
energetics. Oecologia 19: 195-201.
Eschmeyer, W.N. (Editor). 1998. Catalog of
fishes. California Academy of Sciences, San Francisco. 3 vols. 2905 p.
Fryer, G. and T.D. Iles. 1972. Cichlid Fishes
of the Great Lakes of Africa. Oliver & Boyd, Edinburg, UK.
Froese, R. and D. Pauly (Editors). N. Bailly
and M.L.D. Palomares (Translators). 1999. FishBase 99: Concepts, structure, et
sources des données. ICLARM, Manila, Philippines. 324 p.
Groot, G. and L. Margolis. Editors. 1991.
Pacific Salmon Life Histories. University of British Columbia, Vancouver,
Canada. 564 p.
G.S. Helfman, B.B. Collette and D.E. Facey.
1997. The diversity of fishes. Blackwell Science, MA. 512 p.
Ivlev, V.S. 1966. The biological productivity
of waters. [translated by W.E. Ricker]. J. Fish. Res. Board Can. 23: 1717-1759.
Junk, W.J. 1976. Biologia de água doce e
pesca interior, p. 105. In: Relatorio
Anual de INPA, Instituto Nacional de Pesquisas da Amazonia, Manaus.
1758. Systema Naturae per Regna Tria Naturae secundum Classes, Ordinus, Genera,
Species cum Characteribus, Differentiis Synonymis, Locis. 10th ed., Vol. 1.
Holmiae Salvii. 824 p.
Lakoff, G. 1987. Women, fire and dangerous
things: what categories reveal about the mind. University of Chicago Press,
Chicago, 614 p.
Linnaeus, C. 1758. Systema naturae per regna
tria naturae secundum classes, ordinus, genera, species cum characteribus,
differentiis synonymis, locis. 10th ed. Vol. 1. Holmiae Salvii. 824
Mayr, E. 1942. Systematics and origin of
species. Columbia University Press, New York. 334 p.
Nelson, J.S. 1994. Fishes of the world. 3rd
edition. John Wiley and Sons, New York. 600 p.
Palomares, M.L.D. and D. Pauly. 1998.
Predicting food consumption of fish populations as functions of mortality, food
type, morphometrics, temperature and salinity. Mar. Freshw. Res. 49:447-453.
Palomares, M.L.D., C.V. Garilao and D. Pauly.
1999. On the biological information content of common names: a quantitative case
study of Philippine fishes, p. 861-866. In: B. Séret & H,-Y. Sire (eds.)
Proc. 5th Indo-Pac. Fish Conf., Nouméa, 1997.
Pauly, D. 1994. Quantitative analysis of
published data on the growth, metabolism, food consumption, and related features
of the red-bellied piranha, Serrasalmus
nattereri (Characidae). Environ. Biol. Fish. 41:423-437.
Pietsch, T.W. and D.B. Grobecker. 1987.
Frogfishes of the world. Stanford University Press, Stanford, California. 420 p.
Randall, J.E. 1998. Zoogeography of shore
fishes of the Indo-Pacific region. Zoological Studies 37(4):227-268.
Smith, N. 1979. A pesca no rio Amazonas.
Instituto Nacional de Pesquisa da Amazonia, Manaus.
Wakeman, J.M., C.R. Arnold, D.E. Wohlschlag
and S.C. Rabalais. 1979. Oxygen consumption, energy expenditure and growth of
the red snapper (Lutjanus campecheanus).
Trans. Amer. Fish. Soc. 108: 288-292.
Walbaum, J. J. 1792. Petri Artedi Sueci Genera
piscium. In quibus systema totum ichthyologiae proponitur cum classibus,
ordinibus, generum characteribus, specierum differentiis, observationibus
plurimis. Redactis speciebus 242 ad genera 52. Ichthyologiae, pars iii. Artedi
Winberg, G.G. 1960. Rate of metabolism and
food requirements of fishes. Fish. Res. Board Can. Transl. Ser. (194). 239 pp.
Zahavi, A. and A. Zahavi. 1997. The handicap
principle: a missing piece of Darwin's puzzle.
Oxford University Press. 304 p.
This site includes a page with links to Museums and Collections
(click on museums)
Albany Museum - (Freshwater Ichthyology): www.ru.ac.za/departments/am/
American Museum of Natural History: www.amnh.org/
(no link to Department of Herpetology & Ichthyology, however link to
Center for Biodiversity Conservation available at http://research.amnh.org/biodiversity)
Aquatic animals mailing lists maintained by individuals from various
Australian Museum – Ichthyology: www.austmus.gov.au/fish/
BBCWS - Biodiversity and Biological Collections Web Server: www.keil.ukans.edu
Bernice P. Bishop Museum - Ichthyology Department: www.bishop.hawaii.org/bishop/fish/fish.html
Burke Museum, University of Washington, Seattle www.washington.edu/burkemuseum/
California Academy of Sciences - Ichthyology Department: http://web.calacademy.org/research/ichthyology/
Canadian Museum of Nature - Research and Collections - Recherche et
Carnegie Museum of Natural History, Pittsburgh: www.clpgh.org/cmnh/
Chicago Academy of Sciences Nature Museum: www.chias.org/index.html
Coleccion Nacional de Peces (Mexico): www.ibiologia.unam.mx/cnp/acervo.html
FishGopher - The FishGopher Project: www.as.ua.edu/biology/uaic/fishgopher.html
Florida Museum of Natural History - Ichthyology Page: www.flmnh.ufl.edu/fish/
Grice Marine Laboratory, University of Charleston, SC: www.cofc.edu/~grice/
Humboldt State University Fish Collection: http://sorrel.humboldt.edu/~raf1/fish.htm
Illinois Natural History Survey - Fish Collection: www.inhs.uiuc.edu/cbd/collections/fish.html
Instituto Nacional de Pesquisas da Amazônia - Neodat page: http://curupira.inpa.gov.br/colecoes/bdados/neodat/Index.htm
James Ford Bell Museum of Natural History - Fish Collection: www.gen.umn.edu/faculty_staff/hatch/fishes/index.html
(database still under construction)
J. L. B. Smith Institute of Ichthyology: www.ru.ac.za/affiliates/jlb/
Massachusetts Museum of Natural History - Fish collection: http://snapper.bio.umass.edu/vmmnh/fishcoll.html
Milwaukee Public Museum - Vertebrate Zoology Section: www.mpm.edu/collect/vert.html
Museu de Ciências e Tecnologia PUCRS - Laboratório de Ictiologia: http://ultra.pucrs.br/museu/ictio/
Museu Nacional, Universidade Federal do Rio de Janeiro - Setor de
Muséum d'histoire naturelle de la Ville de Genève - Catalogue des
Muséum National D'Histoire Naturelle, Paris – Search: www.mnhn.fr/base/gicim.html
Museum of Comparative Zoology, Harvard University - Fish Page: www.mcz.harvard.edu/fish/
Museum of Southwestern Biology, University of New Mexico - Division of
National Museum of Natural History, Smithsonian Institution - Division
of Fishes www.nmnh.si.edu/vert/fish.html
Natural History Museum (London) – collections: www.nhm.ac.uk/info/collections.html
Natural History Museum of Los Angeles County: http://www.nhm.org/sitemap/
(click on Ichthyology; note that collection database still not available)
Naturhistorisches Museum der Burgergemeinde Bern - (Vertebrate animals -
(under E.A. Göldi collection, click on Gopher, then on Search Pisces
collections; note that this is a downloaded file and may take more than 5
Naturhistoriska Riksmuseet (Swedish Museum of Natural History) –
Collections, Ichthyology Section, Department of Vertebrate Zoology: www.nrm.se/ve/pisces/collpage.shtml.en
Nova Scotia Museum www.ednet.ns.ca/educ/museum/mnh/index.htm
(click Backstage, then Collections,
note that data computerization is incomplete and the collection is not yet
NEODAT - Neotropical Biodiversity Database: www.keil.ukans.edu/~neodat/
Oklahoma Museum of Natural History - Collections and Research: www.snomnh.ou.edu/collections/index.shtml
(Division of Ichthyology is not on line)
Ohio State University’s Museum of Biological Diversity: http://www.biosci.ohio-state.edu/~herb/museum/musehome.htm
(internal link to Museum of Zoology currently not available)
Philadelphia Academy of Natural Sciences: www.acnatsci.org/biodiv/
Provincial Museum of Alberta - Ichthyology Program – Holdings: www.pma.edmonton.ab.ca/natural/fishes/collects/collects.htm
Royal British Columbia Museum - Ichthyology and Herpetology Collection: http://rbcm1.rbcm.gov.bc.ca/research-collectionsdept/nat-hist/section/herpcol.html
Royal Ontario Museum - Centre for Biodiversity and Conservation Biology:
Santa Barbara Museum of Natural History: www.sbnature.org/vertzoo.htm
Scripps Institute of Oceanography - Marine Vertebrates Search: http://www-sioadm.ucsd.edu/siofish/
Staatliches Museum fur Naturkunde, Stuttgart, Germany: http://ourworld.compuserve.com:80/homepages/naturkundemuseum/home-e.htm
Texas Natural History Collection (Austin) - Ichthyology Division: www.utexas.edu/depts/tnhc/.www/fish/
The Field Museum of Natural History, Chicago, Illinois - Fish
Tulane University Museum of Natural History – Fishes: www.museum.tulane.edu/museum/fishes.html
University of Alabama Ichthyological Collections: www.as.ua.edu/biology/uaic/index.html
University of Alaska Museum, Fairbanks - Aquatics collection: http://zorba.uafadm.alaska.edu/museum/aqua/index.html
University of Alberta Laboratory for Vertebrate Paleontology: www.biology.ualberta.ca/wilson.hp/UALVP.html
University of Alberta Museum of Zoology – Collections: www.biology.ualberta.ca/uamz.hp/collections.html
University of Arizona Zoological Collections - Fish Collection: http://eebweb.arizona.edu/collections/fishcoll.htm
University of Arkansas Museum, Fayetteville: www.uark.edu/campus-resources/museinfo/public_html/
University of California Museum of Paleontology - Vertebrate Collection:
University of Georgia Museum of Natural History: http://museum.nhm.uga.edu/mnhrep.html
(Icthyology collection not online).
University of Kansas Natural History Museum - Division of Ichthyology: www.nhm.ukans.edu/~fishes/
(click on Collections)
University of Michigan Museum of Zoology - Division of Fishes: http://ummz1.ummz.lsa.umich.edu/fishdiv/
University of Nebraska State Museum - Division of Zoology www.museum.unl.edu/research/zoology/zoology.html
University of Washington Fish Collection http://artedi.fish.washington.edu/
Virginia Institute of Marine Science - Ichthyology Collection www.vims.edu/ich_coll.html
Western Australia Museum - Aquatic Zoology www.museum.wa.gov.au/nat_sci/aq_zool/aq_zool.htm
Yale University Peabody Museum of Natural History - Ichthyology
Zoological Museum, University of Copenhagen - Ichthyological Section www.aki.ku.dk/zmuc/ver/ichthylo.htm
Zoologisches Museum, Universität Hamburg - Ichthyological Collection www.rrz.uni-hamburg.de/ichthyo/welcome.htm
University of Alberta Ichthyology Web Resources: http://www.biology.ualberta.ca/jackson.hp/iwr/museums.html
The University of British Columbia Library: www.library.ubc.ca
Aquatic Sciences and Fisheries Abstracts: http://www.silverplatter.com/catalog/asfa.htm
 Draft of December 1999. To be tested in the Fish 445 class, January-March, 2000, UBC, Vancouver;
|Last modified by Eli, 17.01.05 (dd.mm.yy)|