Hypostomus commersoni Valenciennes, 1836
Hypostomus commersoni
photo by Equipe de Ictiologia do Nupélia

Family:  Loricariidae (Armored catfishes), subfamily: Hypostominae
Max. size:  60.5 cm TL (male/unsexed); max.weight: 1,832.0 g
Environment:  demersal; freshwater, potamodromous
Distribution:  South America: Lower Paraná including the Iguazú, Paraguay, Río de la Plata and Dulce Rivers.
Diagnosis:  Dorsal spines (total): 2-2; Dorsal soft rays (total): 7-7; Anal spines: 1-1; Anal soft rays: 4-4. This species is distinguished by the following characters: teeth bifid teeth (vs. spoon-shaped); dark spots on a light background (vs light spots on a dark background or not spotted); 4 rough lateral ridges on flanks (vs. absent); 26-29 lateral series plates (vs. < 28 in several species, 31-32 in H. laplatae); 1-2 plates bordering posterior margin of the supraoccipital bone (vs. 3-4 in H. laplatae); differs from H. affinis, H. punctatus, H. ancistroides by having inter-dorsal distance 14.4-19.5% in SL (vs. 18.9-21.0%); head depth 49.0-71.6% in HL (vs. 48.2-49.9); differs from H. spiniger by having fine lateral ridges with odontodes posteriorly inclined (vs. large lateral ridges with odontodes in all directions), weak lateral ridges in caudal peduncle (vs. strong), mid lateral ridge from first plate (vs. ridge from 2nd or 3rd plates); adult of this species (> 12.0 cm SL) can be distinguished from adult H. spiniger by having a strong ridge on temporal plate (vs. very week) (Ref. 121236).
Biology:  Occurs in rivers where substrate from which specimens were obtained was composed chiefly of muddy sand. This species was found in moderately oxygenated waters (6.1-9.1 mg/l) with moderate current; water turbidity 23.7-442 NTU, conductivity 1.087-2.654 μS/cm, pH 7.2-9.2, and temperature 16.8-27.8°C (Ref. 121236).
IUCN Red List Status: Least Concern (LC); Date assessed: 30 October 2020 Ref. (130435)
Threat to humans:  harmless


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