细兵鲶

Overview

The small Gastrodermus gracilis carries an arched dark stripe over a pale body. Where that stripe ends is an important identification clue: it reaches the base of the upper tail rays instead of continuing down onto the lower tail region as in several look-alikes.

Distribution & habitat

Its central Amazon range in Brazil extends from the Juriti in Pará to the Juma in Amazonas. It apparently favors small tributaries with dense bankside vegetation, submerged leaves and branches, and acidic, tannin-stained water. Agricultural conversion and dam construction have damaged some habitats.

Aquarium setup

Use fine sand with sheltered areas formed by roots, branches, and dried leaves. Rounded gravel is another possibility if kept scrupulously clean. The arrangement should give these small fish secure places to withdraw.

Diet & feeding

Provide a varied omnivorous menu of sinking prepared foods and small live or frozen items such as bloodworms and aquatic worms. Ensure that the group receives a deliberate ration. Neither leftovers nor a supposed cleaning role can replace proper feeding.

Behaviour & compatibility

A peaceful, group-living species, it should be kept in a shoal of at least four to six.

Sexual dimorphism

Females generally grow larger and develop a broader, deeper body than mature males.

Breeding

Use two or more males per female where possible. Cooler replacement water and greater oxygenation and circulation can stimulate ripe females. Eggs attach to glass, fine plants, or submerged mops; mops simplify removal.

Separate the brood from adults once laying ends. Maintain matching water and good aeration during incubation, and watch for fungal losses. Hatching normally occurs after three or four days. Tiny live foods, including microworms and brine shrimp nauplii, become suitable once yolk is consumed. Raising the fry requires excellent water quality, and a thin layer of sand appears beneficial compared with a completely bare floor.

Notes

Compare the end of the arched stripe when checking identity rather than relying only on overall pattern. Surface gulps are part of intestinal air breathing. Sharp pectoral spines require careful handling, while suggestions of mildly toxic secretions remain uncertain.