SCOTCAT.COM  

e concentrate this month on the last of the three so called "Dwarf Cory" factsheets. We have compiled already on G. habrosus and G. hastatus and this months subject, G. pygmaeus, is probably the easiest to keep of these three.

Gastrodermus pygmaeus

This small Corydoras/Gastrodermus has a lot going for it as it is easy to keep and breed and has been popular with Cory enthusiasts even although there has been an influx of C-numbers to even challenge the many L-numbers of the huge, in numbers, Loricariidae family.

This Cory has even done well on the show bench at fish shows up and down the country as it is small, and if in good condition can be hard to beat.

Gastrodermus pygmaeus - showing good healthy barbels

G. pygmaeus is a bit like G. hastatus in that it likes to shoal in midwater and as such should be kept in a group of at least six. Substrate can be of fine sand and plants such as java moss and java fern can be used alongside rockwork for further effect. If kept in a species tank for breeding, a fine substrate, java moss and a sponge filter would suffice with weekly 50% water changes to keep the water pure.

Remarks: Corydoras pygmaeus is placed in Lineage 4 which includes two of the dwarf species and a revison would be a resurrection of the disused Microcorydoras (Myers, 1953) with the designated type species: C. hastatus. As of the latest update Corydoras pygmaeus has now been placed in Lineage 5 and has the new genus name of Gastrodermus (2024).

Pygmy Cory

Corydoras pygmaeus

Corydoradinae

South America: Brazil, Tributaries of the Rio Madeira, near Calama. Ecuador, Tributaries of  the Rio Aguarico. Peru, Rio Nanay, west  of the city of Iquitos. Type locality: einem Nebenfluß des Rio Madeira (Brasilien).

Male: 2.5cm (1ins) Female: 3.0cm (1¼ins)

22-26°C (71-79°F)

6.0-7.2.

Head, short and compact.

Ground colour of head and body grey/green. A blackish line runs from the tip of the snout through the junction of the body scutes and ends at the caudal peduncle, where it broadens out into a triangular shape. Dorsal parts of dorsolateral body scutes with darker pigment on the posterior edges. Ventrolateral body scutes creamy white except for a dark line which runs from the ventral fins to the anal fin.

Best kept in a species only tank but can be housed in a small community tank if co-inhabitants are picked carefully; such as small tetras and dwarf rasboras.

Relatively simple, will breed in typical Corydoras T-mating fashion with usually one single egg laid on plants or the aquarium glass, they can lay up to 100 eggs this way. The parents very rarely predate on the eggs. The resulting fry are quick growing on a diet of microworm and crushed flake. You can access the breeding section on Corydoras/Gasstrodermus spawning methods here.

Small foods such as microworm, grindal worm, good quality flake and tablets. Frozen foods such as bloodworm.

Gastrodermus: The lining membrane of the alimentary tract of an invertebrate, used especially when the germ-layer origin is obscure.
pygmaeus: From the Latin pygmaeus = 'dwarf', alluding to its small size.

Alexandrou, Markos & Taylor, Martin. (2011). Evolution, ecology and taxonomy of the Corydoradinae revisited.
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, Phylogenomic analyses in the complex Neotropical subfamily Corydoradinae (Siluriformes: Callichthyidae) with a new classification based on morphological and molecular data, Zoological Journal of the Linnean Society, 2024;, zlae053.
Catfish Association Great Britain: Volume 1. 1983; 138 p.
Fuller, A. M. Ian; Breeding Corydoradine Catfishes. Ian Fuller Enterprises, Kidderminster. 248 p.
Ian A. M. Fuller & Hans-Georg Evers (2011). Identifying Corydoradinae Catfish Supplement 1. Ian Fuller Enterprises.

Photo Credits

Top: © Graham Ramsay
Bottom: © Reinhold Wawrzynski @