Black tetra

Aquarium fish: Black tetra (Gymnocorymbus ternetzi)
Size: 6 cm
Origin: South America
Water temperature: 20-26 ° C
Aquarium volume: 70 l

Black tetra (Gymnocorymbus ternetzi) – freshwater aquarium fish, recommended for beginner aquarists.


The mourner lives in densely vegetated rivers and streams in the Paraguay and Guapore basins and in the Mato Grosso state.

Characteristics and disposition

The mourner is 6 cm long. It is characterized by a high laterally flattened body with dark transverse stripes on a silver background. Males are slightly slender than females, with a clearly wider anal fin and a sharply elongated dorsal fin.

The end of the caudal fin in females is slightly whiter. The fish are also found in several ornamental breeding forms, e.g. the veil mourner, white. Mourners are mobile fish, rather calmly disposed towards other inhabitants. They have a reputation for biting the fins of other fish, but this behavior wears off when kept in larger groups.

There should be at least 6-8 of this species in the aquarium.

Nutrition and feeding

The mourners can be given dry, frozen and live food, such as daphnia, vases, and eyelids.


Due to their lively temperament, they need a lot of space to swim . Fish should be provided with an aquarium with a capacity of min. 70 liters.

They look best in overgrown reservoirs and light muffled by floating plants. In the general aquarium, it can be accompanied by e.g. zebrafish , razbora , cuirass , other tetras or fish from the beautifull family . Due to its high physique, it is also unlikely that it could be included in the menu of larger fish (e.g. scalar ).


It is not difficult to reproduce, however, a spawning tank with dimensions of min. 45x30x30 cm. We put a large portion of moss or an artificial aquarium mop into the aquarium. Mourners can be bred in a group with one male per female. Before the planned spawning, fish are fed with live or frozen food.

When breeding fish in pairs, males and females should be separated into separate tanks with water at a temperature of about 26 ° C and plentifully fed. The water in the breeding tank should be acidic or neutralat a temperature of about 28 ° C. When the females’ bellies will be clearly larger and the males will acquire more intense colors, we choose the thickest female and the most beautiful male and transfer them to the spawning tank in the evening. Spawning should take place first thing in the morning. As soon as we spot roe, we catch some.

Hatching lasts 18-36 hours and the young start swimming after a few days. We feed micro foods in gel or liquid until they are big enough to take live food. Roe and fry in the first days of life are sensitive to light – we darken the aquarium.


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