Corydoras zygatus EIGENMANN & ALLEN, 1942

Black Band 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.

zygatus: etymology is not provided in the original description, but presumably derived from the Ancient Greek ζυγόν (zugón), meaning ‘yoke’, typically used to denote a pair or union. Whether this is in allusion to the colour pattern comprising a dark lateral stripe on the upper portion of each flank, or the species’ similarity to other members of the genus (C. eques and C. macrosteus, the latter currently a synonym of C. aeneus, are mentioned in the description), remains unclear.

Classification

Order: Siluriformes Family: Callichthyidae

Distribution

Known from the Ucayali (río Samiria), Huallaga, Santiago, and Pastaza (ríos Bobonaza and Pindo) river systems in eastern Ecuador and northern Peru. These are all tributary drainages within the middle Río Marañón watershed, a major affluent of the upper Amazon river basin.

Type locality is ‘Río Hallagua system, Yurimaguas (5°54’S, 76°04’W), Loreto, Peru’, which corresponds to the town of Yurimaguas on the Río Huallaga.

Habitat

Few details are available, but some collection records suggest that it inhabits smaller tributaries rather than main river channels.

Maximum Standard Length

60 – 70 mm.

Aquarium SizeTop ↑

Minimum base dimensi0ns of 90 ∗ 30 cm are recommended.

Maintenance

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

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

Water Conditions

Temperature: 20 – 26 °C

pH: 5.5 – 7.5

Hardness: 36 – 215 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 broader and deeper-bodied than males.

Reproduction

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

Use a ratio of two or more males per female if possible, and 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 may be deposited on the aquarium glass, among fine-leaved vegetation or within sunken spawning mops, with the latter particularly recommended since they facilitate easy removal of eggs.

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 are not the easiest to raise, requiring excellent water quality, but seem less susceptible to ailments when maintained over a thin layer of sand rather than in a bare arrangement.

NotesTop ↑

C. zygatus is also known as ‘zygus cory’ in the aquarium trade.

The broad dark stripe in the dorsal portion of the body does not extend into the ventral portion of the caudal peduncle, and this character can be used to distinguish it from the very similar-looking C. rabauti, in which the dark stripe extends ventrally onto the caudal peduncle.

Corydoras 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’s thought that secretions from the axillary glands at the base of each spine may even be mildly toxic or venomous.

References

1. Eigenmann, C. H. and W. R. Allen, 1942 - University of Kentucky: i-xv + 1-494
   Fishes of Western South America. I - The intercordilleran and Amazonian lowlands of Peru. II - The high pampas of Peru, Bolivia, and northern Chile. With a revision of the Peruvian Gymnotidae, and of the genus Orestias.
2. 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.
3. Ferraris, C. J., Jr., 2007 - Zootaxa 1418: 1-628
   Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types.
4. Fuller, I. A. M., and H-G. Evers, 2005 - Verlag A. C. S. GmbH: 1-384
   Identifying Corydoradinae Catfish.