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astrodermus nijsseni is one of possibly four other orange blotched species which are found in the upper Rio Negro drainage in Brazil. The other four which are sympatric with C. nijsseni are: Hoplisoma adolfoi, Hoplisoma duplicareus, Brochis imitator and Corydoras serratus. All these species are variable in their colour patterns.

Gastrodermus nijsseni - female

The main crieria that seperates C.nissseni from the other species is the body shape, very much C.elegans like. If you looked and discounted the colour pattern you would think that you were looking at C. elegans or one of the same body shape i.e. C. nanus or C. napoensis. Of course C. elegans is found many miles away in the south of the country in the Rio Amazonas at Tefé.

Like all the orange-blotched Corydoras from the upper Rio Negro drainage, Gastrodermus nijsseni is very variable in the black parts of the colour pattern. There are forms with broad and forms with very narrow stripes, depending on the locality. The other orange spotted species which are syntopic with Gastrodermus nijsseni mostly show the same variation. The form with a very broad band (only in males), has been erroneously given the C-number C111 (Fuller; Evers, 2005).

Gastrodermus nijsseni - male

The orange head patterns and the black eye mask of all these 5 species must have an advantage when shoaling together as the chance of predation would diminish with such a large group turning one way and then another in a great swarm.

I think a good experiment would be to introduce this species in a largish aquarium maybe 3ft long by 18ins wide and 12ins high with a group of Hoplisoma axelrodi and Brochis imitator and to be able to watch the interaction between these three similar looking Corydoras species.

I have kept and successfully bred this species in the early nineties and like Gastrodermus elegans it likes to swim in the middle layers of the aquarium and like elegans it also lays very small eggs on the tank sides and on the java moss.

I found this quite a timid species and would bolt for cover if disturbed by myself or anyone entering the fishhouse.

The holotype of G. nijsseni was deposited in the Rijksmuseum, Leiden, Germany.

Remarks: Corydoras nijsseni is placed in Lineage 5 and after a revision by "Angelica C Dias, Luiz F C Tencatt, Fabio F Roxo, Gabriel de Souza da Costa Silva, Sérgio A Santos, Marcelo R Britto, Martin I Taylor, Claudio Oliveira 2024" of the genus name Gastrodermus Cope, 1878 it is now Gastrodermus nijsseni.

Common Name

Synonyms

Family

Callichthyidae

Subfamily

Distribution

Size

Temp.

p.H.

Characteristics

Colouration

Aquarium Care & Compatibility

Sexual Differences

The males tend to be slightly smaller and more slender than the females and have a more ornate pattern whereas the females look plainer. The ventral fins of the males tend to be more pointed than those of the females. Sexing of these catfish is easier when being viewed from above.

Reproduction

Diet

Glossary of Terms

Etymology

References