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FACTSHEETS: July 2009 - no. 157

Gastrodermus pygmaeus Knaack, 1966


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

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

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).

 

Common Name

Pygmy Cory

Synonyms

Corydoras pygmaeus

Family

Callichthyidae

Subfamily

Corydoradinae

Distribution:

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).

Size

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

Temp.

22-26°C (71-79°F)

p.H.

6.0-7.2.

Characteristics

Head, short and compact.

Colouration

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.

Aquarium Care & Compatibility

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.

Reproduction

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.

Sexual Differences

Females are noticably heavier when in breeding condition. They also grow larger than the smaller males.

Diet

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

Glossary of Terms

Anal Fin: The fin forward from the anal cavity.
Caudal Peduncle: The area between the dorsal fin and the tail.
Dorsolateral: Extending from the top to the side.
Ventral Fin: The paired fins, between the pectorals and the anal fins.
Ventrolateral: Extending from below and to the side.

Etymology

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.

References

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 @   Catfish and more

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ScotCat Sources

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