韦氏杂色脂鲤 · Black Darter Tetra

Overview

Small size does not make Poecilocharax weitzmani a conventional schooling tetra. Males defend territories vigorously, dry food is usually refused, and shipping can leave fish in poor condition. Reliable live food and stable soft acidic water should be prepared in advance.

Distribution & habitat

Records include Brazil, Colombia, Peru, and Venezuela, notably upper Negro, Orinoco, and Solimões drainages. The Inírida and Casiquiare are included among Orinoco-related sites. Brazilian and Colombian fish tend to be more intensely colored; Peruvian populations may represent an undescribed species, but that remains unresolved.

Slow rainforest streams commonly have mud or sand, abundant leaves, and submerged roots. Canopy and bank vegetation provide shade. The tea-colored water is mineral-poor and weakly buffered.

Aquarium setup

A pair or one male with several females can use roughly 45 × 30 cm of floor space. With multiple males, allow at least about 30 × 30 cm per male and ample retreats; trapped subordinates can suffer serious fin damage.

Use soft sand, roots, branches, and leaves to create several shaded areas. Suitable tubes provide retreats and spawning cavities. Dim light, floating cover, and tolerant ferns, mosses, or Cryptocoryne work well. Gentle air-driven filtration is adequate, but the aquarium must be mature and stable.

Diet & feeding

It is a micropredator, thought to take insect larvae, crustaceans, and worms, possibly with some fry. The exact wild prey mix remains tentative.

Dry foods are usually rejected. Daily live Daphnia, Artemia, grindal worms, microworms, or chopped bloodworms are commonly needed after import. Avoid severely hollow-bellied specimens, which seldom recover.

Behaviour & compatibility

It competes poorly and should receive priority in any community. Avoid other bottom dwellers, especially territorial ones. Similar-sized peaceful pencilfishes, hatchetfishes, and small characins using upper water are better candidates; appropriate small armored catfishes may also work.

It does not form schools. A pair is possible, while multiple-male groups require enough room and cover to accommodate vigorous rivalry. More females than males helps distribute attention.

Sexual dimorphism

Males are larger and more colorful, often developing extended dorsal and anal fins. Not every male develops equally long fins, and the difference does not appear to reflect dominance alone.

Breeding

Provide caves or short tubes, approximately pH 4.0–5.0, very low hardness and conductivity, and abundant small live foods. A male defends one or more caves, intensifies in color, and develops thicker-looking white pelvic-fin tips. Ripe females become dark with a vivid red anal fin and inspect male territories.

Approximately 50–100 eggs usually attach to the cave roof. The male guards them, circulates water with tail movements, and removes infertile eggs. Hatching begins after about four or five days; young drop to the cave floor around two days later.

A second female may spawn while an earlier clutch is incubating, normally without damaging it. Transfer the first brood once freely swimming to improve survival of the later one. Free-swimming fry immediately take Artemia nauplii, and paternal care ends then. Separate adults and fry and feed the male well, since he commonly fasts during care.

Notes

Also traded as Black Morpho, it often arrives in small numbers among other wild-caught fishes. Members of its genus lack an adipose fin. The function of unusual cranial openings and nearby fatty tissue remains unclear; thermal prey detection is a hypothesis rather than an established ability.