Scleromystax macropterus (REGAN, 1913)

Sailfin 'Cory'

SynonymsTop ↑

Corydoras macropterus Regan, 1913; Corydoras bertoni Eigenmann, 1942

Etymology

Scleromystax:  from the Ancient Greek σκληρός (sklērós), meaning ‘hard’, and μύσταξ (mústaks), meaning ‘upper lip’.

macropterus: from the Ancient Greek μακρός (makrós), meaning ‘long’, and πτερόν (pterón), meaning ‘fin’, in reference to the extended dorsal-fin in adult males.

Classification

Order: Siluriformes Family: Callichthyidae

Distribution

Known from minor rivers in the coastal states of São Paolo, Paraná, and Santa Catarina, southern Brazil, plus some tributaries of the rio Paraná basin in Paraguay.

Type locality is ‘Paranaguá, 25°32’S, 48°36’W, Paraná, Brazil’.

Habitat

Mostly collected from small, blackwater streams draining directly into the Atlantic Ocean, but is also known to inhabit roadside ditches and other such environments.

Maximum Standard Length

80 – 90 mm.

Aquarium SizeTop ↑

Minimum base dimensions of 120 ∗ 45 cm or equivalent are recommended.

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, particularly if you wish to keep two or more males together.

Water Conditions

Temperature: 14 – 20 °C

pH: 5.0 – 7.0

Hardness: 18 – 143 ppm

Diet

Scleromystax spp. are foraging omnivores, and most will accept 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 ↑

Males are somewhat territorial towards one another and should not be maintained together in smaller aquaria, otherwise peaceful.

Sexual Dimorphism

Males are more intensely-patterned and possess longer pectoral and dorsal fins than females.

Reproduction

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

Use a ratio of a single males per female in order to avoid rival males concentrating on each other, and when the female is 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 ↑

The genus Scleromystax 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 is 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. Regan, C. T., 1913 - Annals and Magazine of Natural History (Series 8) v. 11 (no. 62): 231-232
   Descriptions of two new fishes from Paranagua, Brazil, presented to the British Museum by Herr A. Rachow.
2. Ferraris, C. J., Jr., 2007 - Zootaxa 1418: 1-628
   Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types.
3. Fuller, I. A. M., and H-G. Evers, 2005 - Verlag A. C. S. GmbH: 1-384
   Identifying Corydoradinae Catfish.
4. 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.