大鳍兵鲶 · Sailfin 'Cory'

Overview

Extended dorsal and pectoral fins help identify male Scleromystax macropterus. This cool-water armored catfish is generally mild, but males may dispute territories. Space and sex ratio therefore matter as much as the number of fish in a group.

Distribution & habitat

It is known from small rivers in the southern Brazilian coastal states of São Paulo, Paraná, and Santa Catarina, and from Paraná-basin tributaries in Paraguay. Most collections come from small blackwater streams flowing directly to the Atlantic, although roadside ditches are also used.

Aquarium setup

Provide a minimum footprint around 120 × 45 cm. Fine sand is preferable, with thoroughly cleaned smooth gravel an alternative. Other decor is flexible, but shelter is important, particularly if several males are contemplated. Respect the species' preference for cool conditions.

Diet & feeding

Combine sinking dry foods with small live or frozen items, including bloodworms and Tubifex. Feed directly and offer variety. It should not be left to survive on food missed by other fish or expected to perform aquarium maintenance.

Behaviour & compatibility

Male-to-male territorial behavior is the main limitation; otherwise the species is relatively peaceful. Several males should not share a smaller tank, even if hiding places are present.

Sexual dimorphism

Males have more vivid patterning and longer dorsal and pectoral fins than females.

Breeding

Pair one male with one female to avoid rival males focusing on each other. A female full of eggs can be stimulated with a cooler water change of around 50–70%, increased aeration, and additional flow, repeating if necessary.

Eggs attach to glass, fine plants, or submerged spawning mops. Mops make transferring the clutch easier. Separate eggs and adults after spawning. Use matching water and ample oxygenation in a separate hatching container, and manage fungal losses. Eggs usually hatch in about 3–4 days. Once the yolk is absorbed, offer microworms or Artemia nauplii. Excellent water quality is needed during rearing, and a thin sand layer appears helpful compared with a bare floor.

Notes

Bony plates replace scales, while occasional air gulps supplement respiration. The pectoral spines can pierce skin and should be handled carefully. Secretions near their bases may be mildly toxic, though this remains uncertain. The long fins reflected in the species name are particularly evident in mature males.