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Corydoras nijsseni  Sands, 1989

orydoras 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: C. adolfoi, C. duplicareus, C. imitator and C. serratus. All these species are variable in their colour patterns.

Corydoras nijsseni = female

Corydoras 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, Corydoras 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 Corydoras 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).

Corydoras nijsseni  = male

Corydoras 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 C.axelrodi and C.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 Corydoras 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 C. nijsseni was deposited in the Rijksmuseum, Leiden, Germany.

Dorsal: 1,7; Dorso-lateral scutes: 21; Ventro-lateral scutes: 19. The pectoral spines are thorned on the posterier edge with the anterior edge being barely serrated.

Dark head, almost to the posterior edge of the eye. Orange band behind the eye but anterior to the dorsal fin at which point, a dark, typical 'adolfoi/imitator' narrow black line arises and extends from the dorsal fin laterally to the caudal fin. All the fins are clear of pigment.

Like most species of Corydoras they are peaceful and and would do fine in a community aquarium with smaller compatriots such as small Tetras and Rasboras.

Lays their eggs in Corydoras fashion on the glass sides and plants especially in the fronds of Java Moss plants.  For more information on the breeding of the many varieties of Corydoras you can find many articles in the Breeding Articles section.

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.

As with all Corydoras they accept a mixed and varied diet. Good quality flake foods, granular and tablet foods, cultured whiteworm, grindal worm and frozen foods such as bloodworm.

Glossary of Terms
Sympatric: Referring to two or more species living in the same or overlapping geographical area.
Dorso-lateral scutes: The bony covering extending from the top to the side.
Ventro-lateral scutes: The bony covering extending from below and to the side.

Cory = helmet, Doras = skin.
nijsseni = Named in honour of Dr. Han Nijssen of the University of Amsterdam.

Fuller, A.M. & Evers, Hans-Georg: Identifying Corydoradinae Catfish P.182-183
Sands, David; Two New Species of Corydoras: Aquarist and Pondkeeper August 1990.

Photo Credits
Top:        Allan James @ ScotCat

Bottom:  Ian Fuller @ 
    Corydoras World
Factsheet 135

Common Name:
South America: Brazil Brazil; Main whitewater tributaries of the Rio Negro and upriver from Sao Gabriel da Cachoeira
4.5cm ( 1¾ins)
23-27°C (73-81°F)    
6.0 -7.2.
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                                                                                                                                     Factsheet 135 = updated December 14, 2018 , © ScotCat 1997-2018 Go to Top