Black Tetra

About

The black tetra (Gymnocorymbus ternetzi) is one of those fish that has been a staple of the hobby for decades, and for good reason. Native to river basins in Paraguay, the Guaporé region, and down toward Argentina, it naturally occupies the middle and upper water column, where it cruises in loose groups picking off worms, small crustaceans, and insects. The bold, deep black coloration that makes juveniles so dramatic does soften with age, but adults still carry enough contrast to stand out against more colorful tankmates. In the aquarium, this species earns its reputation as a solid community fish. It gets along well with livebearers, danios, rasboras, Corydoras, and even more robust dwarf cichlids. Its somewhat rounded body shape also means larger fish like angelfish rarely view it as food. The main caveat is fin nipping. A well-documented tendency that is largely manageable by keeping a proper shoal of at least a dozen individuals, which redirects most squabbling inward. All fish in the trade are captive bred, making them forgiving of a wide range of water conditions. One thing worth noting: dyed specimens have appeared on the market in recent years, injected with artificial colors. Best avoided entirely. The long-finned and leucistic "white skirt" varieties are legitimate selectively bred forms and generally quite healthy.