Black Tetra

The Black Tetra has a high, laterally compressed body, and its size in an aquarium rarely exceeds 5.5 cm. Distinctive features include two clear vertical bands on the front part of the body, as well as large dorsal and anal fins. The size and shape of these fins resemble a lush skirt, which, combined with the fish's dark coloration, led to the name "Black Widow." With age, the Black Tetra's coloration usually becomes lighter. Differences between male and female Black Tetras are evident in the shape and size of their fins. In males, the dorsal fin is more pointed, and the anal fin is uneven in height—it is longer near the belly and noticeably lower towards the tail. In females, the "skirt" (anal fin) is usually symmetrical, and they also have a larger abdomen.

The Black Tetra was first described by Belgian zoologist Albert Boulenger in 1895. Its natural habitat is in South America — the Rio Paraguay and Guaporé basins in Brazil, Bolivia and Argentina. Here, the fish inhabits the upper layers of slow-moving waters, preferring small, shaded forest rivers and streams. The Black Tetra's diet in the wild consists of small worms, crustaceans, and insects.

The Black Tetra is an active schooling species, so it is recommended to keep them in groups of at least 8 individuals. With fewer fish, they may become excessively timid. Their activity somewhat decreases with age. When choosing tank mates, select fish of similar size and temperament; it is strongly not recommended to house Black Tetras with smaller species.

A key requirement for keeping Black Tetras is ensuring water purity. An efficient filter and regular water changes (25%-50% of the volume every two weeks) successfully handle this task. Given that this fish prefers subdued light, additional lighting may not be necessary if the aquarium is in a well-lit room. Otherwise, special lamps will be indispensable. In terms of aquarium decor, low-growing plants planted in groups are welcome; preference should be given to shade-loving species that thrive in low light. The bottom should ideally be covered with dark fine gravel or coarse sand, and driftwood, pieces of wood, and intertwined roots can be used as decorations.

Although in its natural environment the Black Tetra primarily feeds on high-protein food, in a home aquarium it readily accepts dry commercial foods such as flakes and granules. A wide range of specialized foods for Tetras is available on the market, enriched with all necessary elements, including freeze-dried products from crustaceans and zooplankton. For dietary variety, bloodworms or large daphnia can be offered periodically.

Spawning of Black Tetras is preferably organized in a separate tank, as this species tends to eat its own fry. A 20-liter volume is sufficient for a breeding tank, with the water composition being identical to that of the main aquarium. Equipment required includes a filter, heater, air stone, and light source. The decor should include groups of low-growing plants and a sandy bottom. Spawning can begin at any moment, signaled by the female's enlarged abdomen, which indicates readiness for the pair to be moved to a separate tank. After some time, the female releases eggs into the water, and the male fertilizes them. The entire process occurs over plant thickets, where the eggs subsequently settle. If plants are planted in several groups, the pair may lay eggs in multiple areas. Upon completion of spawning, the adult fish are returned to the main aquarium. It is recommended to cover the breeding tank with a towel for a couple of days, during which the fry will hatch. At this point, lighting must be turned on, otherwise the fry will not be able to find food in dim light or darkness. Fry should be fed micro-foods or Artemia nauplii.

When optimal keeping conditions are met, the risk of disease in Black Tetras is extremely low. However, under unfavorable conditions, they may be susceptible to typical diseases of tropical aquarium fish.

When choosing Black Tetras, prioritize active individuals with clean scales and undamaged fins. Avoid fish with signs of lethargy, white film on the body, ulcers, or an unnaturally swollen abdomen. Healthy Black Tetras should show curiosity, stay in a school, and react quickly to external stimuli. It is important to note that artificially colored or genetically modified individuals are often found in stores. When purchasing such fish, it is recommended to carefully inspect them for any skin damage resulting from the coloring procedure. If possible, ask the seller about the keeping conditions and diet the fish are accustomed to, to minimize stress during their transfer to a new aquarium.