Corydoras burgessi AXELROD, 1987

Burgess' Cory

Etymology

Corydoras: from the Ancient Greek κόρυς (korus), meaning ‘helmet’, and δορά (dora), meaning ‘skin, hide of an animal’, in allusion to the rows of bony plates on the flanks of genus members.

Classification

Order: Siluriformes Family: Callichthyidae

Distribution

Apparently endemic to the upper rio Negro basin in Brazil, although detailed records do not currently exist.

Type locality is ‘Rio Unini, tributary of Rio Negro, Amazonas, Brazil’.

Specimens for the aquarium trade are apparently collected in the vicinity of São Gabriel da Cachoeira which is type locality for the similar-looking C. adolfoi (see ‘Notes’).

Habitat

Habitats in the rio Negro mostly comprise pristine blackwater tributaries and areas of flooded forest where the water is characteristically stained dark with organic chemicals, although some clear water habitats also exist.

Such environments typically contain tea-coloured water with very little detectable hardness, low conductivity, and a pH of 4.0-6.0, with other fishes comprising small characids, lebiasinids, and dwarf cichlids of the genus Apistogramma.

Maximum Standard Length

50 – 55 mm.

Aquarium SizeTop ↑

Base dimensions of 80 ∗ 30 cm or equivalent are recommended for long-term care.

Maintenance

Ideally use a substrate of fine sand, although rounded gravel is an acceptable alternative provided it’s kept scrupulously clean.

Other décor is largely down to personal choice, but some cover should be provided to give the fish security.

Driftwood branches and dried leaf litter are useful additions, the latter in particular driving establishment of microbe colonies as decomposition occurs. Such microorganisms can provide a valuable secondary food source for fry, whilst the tannins and other chemicals released by the decaying leaves are also thought beneficial and help simulate natural conditions.

Filtration need only be gentle with an air-powered sponge-style unit normally adequate, although a degree of water movement is acceptable.

Water Conditions

Temperature: 20 – 28 °C

pH: 5.0 – 7.0

Hardness: 18 – 179 ppm

Diet

Corydoras spp. are foraging omnivores and will accept most sinking dried foods, as well as small live and frozen varieties such as chironomid larvae (bloodworm), Tubifex, etc. Feeding a varied diet will ensure the fish are in optimum condition.

Under no circumstances should they be expected to survive on ‘left-overs’ from other inhabitants of the aquarium or relied on to ‘clean’ the aquarium.

Behaviour and CompatibilityTop ↑

Peaceful and gregarious. Should be maintained in a  group of at least 4-6 individuals.

Sexual Dimorphism

Females tend to grow larger, and sexually mature individuals are noticeably rounder and broader-bodied than males, especially when gravid.

Reproduction

Can be bred in a similar fashion to many other Corydoras species.

Use a ratio of two males per female if possible. When the females are visibly full of eggs perform a large (50-70%) water change with cooler water, and increase oxygenation and flow in the tank. Repeat this daily until the fish spawn.

Eggs are normally deposited on the aquarium glass, but it is recommended to provide alternatives in the form of fine-leaved vegetation or fine spawning mops.

Once spawning is complete either adults or eggs should be removed; the latter can usually be rolled gently up the glass with a finger. The new container should contain the same water as the spawning tank and be similarly well-oxygenated.

Most breeders add a few drops of methylene blue, or an alder cone or two at this point in order to prevent the eggs developing fungus.

Incubation is normally 3-4 days and once the fry have fully-absorbed their yolk sacs they are able to accept small live foods such as microworm, Artemia nauplii, etc.

They require excellent water quality, but seem less susceptible to ailments when maintained over a thin layer of sand rather than in a bare-bottomed arrangement.

NotesTop ↑

This species is one of a number of similarly-patterned congeners, including C. adolfoi, C. davidsandsi, C. duplicareus, C. imitator and the unidentified C. sp. ‘C121’.

The most obvious distinguishing characters are that the black marking in the upper part of the body is restricted to the area beneath the dorsal-fin and extends into the majority of the fin , while the paler patch anterior to it, on top of the head, is yellowish rather than orangish.

Additional diagnostic characters have proven unavailable thus far since it was described in a hobbyist magazine which is difficult to obtain.

The existence of multiple, similarly-coloured species which coexist and sometimes form mixed schools is relatively common in the genus. In some cases Corydoras colour patterns have even evolved in other taxa, such as certain members of the genera Otocinclus, Brachyrhamdia, and Serrapinus. The reason for the success of such patterns is thought to be protection from predators in that they feature cryptic or otherwise disruptive details such as stripes, reticulations, or strongly-coloured fin spines. Similarly-patterned species may therefore have evolved to take advantage of foraging in a larger group while simultaneously adapting to exploit contrasting ecological niches. In Corydoras, this is typically expressed via differences in snout length, mouth position, or body size.

The genus Corydoras is among the largest catfish groups and currently contains over 150 valid species. It is included in the family Callichthyidae, of which members are often referred to collectively as ‘armoured’ or ‘mailed’ catfishes group due to the presence of bony plates in place of scales on the body.

Their taxonomy can be confusing, and numerous undescribed species are also thought to exist. Fish of unconfirmed identification entering the aquarium hobby are therefore typically assigned a ‘C‘ or ‘CW‘ number for purposes of reference and organisation.

They are facultative air breathers and possess a modified, highly vascularised intestine which has evolved to facilitate uptake of atmospheric oxygen and aid survival in oxygen-deprived environments. In the aquarium you’ll occasionally see them rising to the surface to take in gulps of air.

The stiffened pectoral-fin spines are capable of piercing human skin and a ‘sting’ can be very painful indeed, so care should be exercised when handling them. It is thought that secretions from the axillary glands at the base of each spine may even be mildly toxic or venomous.

References

1. Axelrod, H. R., 1987 - Tropical Fish Hobbyist 35(12): 22-25
   Two new species of catfishes (Siluriformes, Callichthyidae and Pimelodidae) from the Rio Unini, Amazonas, Brazil.
2. Alexandrou, M. A., C. Oliveira, M. Maillard, R. A. R. McGill, J. Newton, S. Creer, and M. I. Taylor, 2011 - Nature 469: 84-89
   Competition and phylogeny determine community structure in Müllerian co-mimics.
3. Britto, M. R. and F. C. T. Lima , 2003 - Neotropical Ichthyology 1(2): 83-91
   Corydoras tukano, a new species of corydoradine catfish from the rio Tiquié, upper rio Negro basin, Brazil (Ostariophysi: Siluriformes: Callichthyidae).
4. Ferraris, C. J., Jr., 2007 - Zootaxa 1418: 1-628
   Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types.
5. Fuller, I. A. M., and H-G. Evers, 2005 - Verlag A.C.S. GmbH: 1-384
   Identifying Corydoradinae Catfish.
6. Greven, H., T. Flasbeck and D. Passia, 2006 - Verhandlungen der Gesellschaft für Ichthyologie, Band 5: 65-69
   Axillary glands in the armoured catfish Corydoras aeneus (Callichthyidae, Siluriformes).
7. Reis, R. E., S. O. Kullander, and C. J. Ferraris, Jr. (eds) , 2003 - EDIPUCRS, Porto Alegre: i-xi + 1-729
   Check list of the freshwater fishes of South and Central America. CLOFFSCA.