Black widow tetra

Behaviour and habits

The black widow tetra is a hardy, deep-bodied shoaler that is lively but can be a little boisterous. Kept in a group of six or more it is a fine community fish, but in twos or threes it may nip the long fins of tankmates, so the group size is part of its care. It swims mid-water and looks best against a backdrop of green plants.

What to feed, and how often

It takes almost anything: flake, micro-pellet and frozen foods such as daphnia and bloodworm. Feed once or twice a day, offering only what clears in a minute or two; a varied diet keeps the black body deep and the fins tidy.

Water changes and maintenance

Change about 25% of the water each week, matched closely to the tank. The black widow is adaptable to a range of water, but it dislikes sudden swings, so match temperature and chemistry and keep the tank clean.

Care and how easy it is

An easy, forgiving tetra for a community tank, provided it has a proper group and enough swimming space. Avoid mixing it with very long-finned or delicate fish.

Lifespan

With good conditions and steady water quality, this species typically lives around 3–5 years in a home aquarium; some individuals live longer.

Common health problems

Hardy; the usual issues are fin rot or ich in poor water, and torn fins from nipping or sharp décor.

If it gets sick

Keep the water warm and clean and the group large, and treat any fin damage or spots early rather than waiting for them to spread.