Black Widow Tetra
Gymnocorymbus ternetzi
Black Widow Tetra is a small South American characin best known in the aquarium trade for its deep-bodied silver fish with dark vertical bars and a black rear half. It is a hardy schooling species that does best in planted, gently filtered freshwater tanks.
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Identification points
- Deep, laterally compressed silver body with two broad black vertical bars behind the gill area
- Distinct darkening over the rear half of the body and fins, especially the dorsal and anal fins
- Small characin profile with a forked tail and translucent fins in juveniles to adults
Habitat
In nature it inhabits slow-moving, vegetated freshwater streams, floodplain waters, and calm tributaries in subtropical South America, especially in warm, soft to moderately hard water with cover from plants and submerged roots.
Bait notes
Not a sport-fishing species and is rarely targeted by anglers. In aquaria it readily takes quality flakes, micro pellets, frozen daphnia, brine shrimp, and bloodworms; live small invertebrates are accepted enthusiastically.
Behavior
An active midwater shoaling fish, it feeds on small insects, worms, crustaceans, and other tiny invertebrates. It is generally peaceful but can nip fins if kept in too-small groups or with long-finned tankmates.
Caution
Aquarium species only; do not release into local waters. Like many tetras, it can be stressed by poor water quality and sudden parameter changes. Fin-nipping may occur in cramped setups or mixed with slow, long-finned fish.
Fishing notes
No practical angling methods apply for this ornamental species. For aquarium maintenance, keep it in groups of 6 or more, provide plants and open swimming space, and use subdued conditions to reduce stress.