Scleromystax barbatus

Order: Siluriformes
Suborder: Loricarioidei
Family: Callichthyidae
Subfamily: Corydoradinae
Genus: Scleromystax
Species: Scleromystax barbatus, Quoy & Gaimard, 1824

Scleromystax barbatus is one of the largest growing species of the Corydorinae subfamily. With a size of around 9 - 12 cm this species is fully grown.

S. barbatus shows a long body with a long snouted head. The fins are relatively long. Males develop a beard like growth on the sides of the head.

The coloration of S. barbatus is beige-golden with a black pattern all over the body. In the fins, this pattern is more striped. On the back end of its body big black stains are visible. In the head- and front body region the black pattern changes into fine worm lines. Males show a more black and gold contrast, where as females are more brownish. This sexual dichromatism is really rarely seen in Corydorinae.

S. barbatus is a calm fish which likes to swim in big groups over sandy substrate, to search for food all day. It sometimes shows fighting behaviour between males of its kind but is other than that a peaceful fish. As a defend mechanism, S. barbatus spreads its dorsal and pectoral fins. The hard rays of those fins are pointy and cause burning wounds, which makes it difficult for predators to swallow the fish as a whole, since they get stuck in most cases in the mouth or throat of bigger fish.

As other members of its subfamily, also S. barbatus gives of poisonous substances when stressed, which can even affect members of its own species. In captivity this behaviour can be observed, when fish are packed in bags for shipping/transport. To avoid the poisoning and therefore death of the fish, active charcoal granules should always be added in transport bags. The charcoal binds poisonous substances in the water.

The distribution of this fish is the east coast of Brazil. Other than many members of its subfamily, this fish is found in subtropical climate which shows slight changes in temperature between the seasons. This fish is found in fast streaming rivers of the coastal drainages of Rio de Janeiro till Santa Catarina.

The homewaters of S. barbatus show rather cold water temperatures of 18 - 24 °C. Also this member of Corydorinae can breathe atmospheric oxygen, which gets swallowed with the mouth above the water and used up in the darm. This means this fish can also survive low oxygen levels in the water. In its habitat a pH of 6 - 8 is found and makes this species therefore a robust fish for the aquarium.

The substrate of its habitat contains mostly of bright, fine sand. Here and there some fallen leafs, branches and twigs can be seen laying on the ground.

Scleromystax barbatus is an omnivorous fish which basically eats everything small enough to fit into its mouth. The more correct term would be detritovore, since this fish searches and chews through the muddy and sandy substrates of its habitat. For that, S. barbatus dives deep with its long snout into the substrate and digs through it.

In Nature its diet consists mostly of worms, insect larvae and smaller pieces of detritus. Also small fish larvae, and crustaceans are welcomed food.

In captivity this fish is not a picky eater. Even though it prefers more natural food, like frozen artemia, mosquito larvae etc. it also accepts industrial food, like granules, flakes and tabs. The diet should contain more animal proteins than plant matter, but both parts are important for keeping Scleromystax healthy.

This fish grows big and likes to swim a lot over the day. Therefore a tank from 100 - 120 cm length should be the minimum size for longer keeping. This species should always be kept in groups of at least 6 pieces to feel comfortable and not to show signs of being shy.

The most important thing is to keep this species not to warm. Most home aquariums for tropical fish are above 25 °C, which is to warm for long term keeping of Scleromystax. A temperature of 16 - 24 °C is ideal. With an pH range from 6 - 8, this species seems to get along with a lot of different water types.

Since a heater is not necessary in a tank for this species, the only other technical equipment would be a filtration, lights, and a streaming pump. This species prefers clear mediate streaming water and bright light. Weekly waterchanges with cold water are very welcomed by this species and help to keep the temperature low.

As substrate always fine sand should be used. To rough broken gravel can damage the mouth and barbels, which mostly get infected by bacteria and cause the death of the fish. S. barbatus likes to wash its gills with fine sand. As hiding spots some bigger stones or pieces of driftwood with some stone plates on top can be used. Also water plants are a welcomed hiding and spawning spot.

This species should only be put together with fish that can stand colder water temperatures. Other than that, bigger cichlids or other predators should be avoided, since they could try to swallow the fish, which leads to the death of both involved ones. Tetras or life bearers are the ideal fish to integrate into a tank for Scleromystax.

The easiest way to sex S. barbatus is the coloration. Adult males show a contrasty black and golden coloration, where as females stay greyish-brown. Males can show this coloration when stressed.

Adult males also develop a beard growth on the sides of the head.

Females are more robust and not to slim built as males. Additionally females show more rounded belly fins, which help carrying the eggs to the spawning site.

S. barbatus gets sexually mature with around one year of age. Mostly triggered by fresh and cold water several males start to follow a round female. T-position can be observed where the female puts her head to the genital region of the male.

The female forms then a pocket with the belly fins, in which she lays her eggs. These eggs get transported to the spawning substrate, which can be everything from plants, to stone- or wood surfaces. In captivity also against glass or in so called "spawning mops" the eggs are deposited. Males follow mostly to fertilize.

These eggs hatch best in slightly acidic parameters of 6 - 6,5 pH after a few days. Eggs can be rolled of the surface with the tip of the finger and transferred into a incubation container. This prevents other fish to eat the eggs. The eggs can be incubated in water with the same parameters but with an air stone and a catappa leave added.

Ones the fry hatch, they eat 1-3 days from their yolk sac. After using up the yolk, the fry can be fed with small living food, like brine shrimp (Artemia) nauplii or microworms. The bigger the fry get, the more space and bigger food they need.