Easy to intermediate
Chocolate Cherry Shrimp (Neocaridina davidi)
18–26°C · pH 6.5–8 · 30L
£13.99
Black Widow Tetra (Gymnocorymbus ternetzi), a hardy active schooling tetra for mature community aquariums with open swimming space.
Adult size is the maximum length this species reaches at full maturity (scientific sources). The livestock you receive will be younger and smaller — pick a size variant above for the actual shipping size. Photos are AI-enhanced, so the animal may show subtle colour or marking differences.
Gymnocorymbus ternetzi
Black Widow Tetra are a shoaling species — they need 6+ to feel safe and show their full colour.
Black Widow Tetra (Gymnocorymbus ternetzi), a hardy active schooling tetra for mature community aquariums with open swimming space.
Adult size is the maximum length this species reaches at full maturity (scientific sources). The livestock you receive will be younger and smaller — pick a size variant above for the actual shipping size. Photos are AI-enhanced, so the animal may show subtle colour or marking differences.
Maintain these water conditions for optimal health and vibrant colors
Black Widow Tetra (Gymnocorymbus ternetzi), also known as the Black Skirt Tetra or Black Tetra, is a hardy South American characin for active community aquariums. It has a silver front half, darker rear body and deep skirt-like anal fin, giving a strong contrast against plants, wood and lighter shoaling fish.
This is an in-stock live-fish listing with multiple size options under the same Shopify product. Orders are packed for UK live-fish courier delivery, covered by our Live Arrival Guarantee, and first-time customers can use WELCOME10 where eligible.
| Common names | Black Widow Tetra, Black Skirt Tetra, Black Tetra |
|---|---|
| Scientific name | Gymnocorymbus ternetzi |
| Adult size | Usually around 5-6 cm |
| Temperament | Active and generally peaceful, but can nip slow long-finned fish if cramped or kept in too small a group |
| Best group size | Six minimum; eight or more is better |
| Tank level | Middle to upper water |
| Temperature | 22-28 C, with stable tropical conditions preferred |
| pH | About 6.0-7.5 |
| Minimum aquarium | 60 litres for a small group; 75-90 litres or more for a stronger display |
Gymnocorymbus ternetzi is a classic tetra because it is adaptable, visible and easy to feed, but it should still be treated as an active schooling fish rather than a background filler. Young fish often show the darkest markings, while older individuals can become more silver-grey with a softer black skirt. That colour change is normal and does not mean the fish is unhealthy.
The body shape is deeper than many slim tetras, so a group looks substantial even at modest size. Use a darker background, green plants and open swimming lanes to show off the contrast. Avoid confusing this listing with substrate-focused fish: Black Widow Tetras are midwater characins, not substrate fish.
This cleanup keeps the existing aquarium display images and adds the exact Petra source photo for SKU 2102 as the supplier-backed reference image. The source image helps confirm the real deep-bodied tetra profile, dark fin pattern and supplied fish identity. No existing product images are removed.
Provide a mature aquarium with open swimming space through the middle, planting around the sides and back, and enough cover to break up sight lines. A 60-litre tank can hold a small group, but Black Widow Tetras show better behaviour in 75-90 litres or more. They are not delicate fish, but cramped groups are more likely to chase or nip.
Filtration should be mature and steady, with moderate water movement. They do not need specialist blackwater conditions, but subdued lighting, wood, plants and a darker substrate help them look calmer and more attractive. Avoid adding them to an uncycled tank, and keep ammonia and nitrite at zero.
This species adapts to a reasonably broad range of community-aquarium conditions, which is one reason it remains popular. Aim for 22-28 C, pH around 6.0-7.5 and stable, clean water. Do regular partial water changes and avoid sudden shifts in temperature or chemistry.
Keep at least six, with eight to twelve preferred where space allows. A proper group keeps social behaviour within the shoal and reduces the chance of tank mates being bothered. If you keep only two or three, the fish may become nervous, faded or pushy.
Black Widow Tetras are omnivores that readily take quality flakes, small granules and micro pellets. Rotate frozen or live foods such as daphnia, cyclops, brine shrimp, mosquito larvae and bloodworm pieces to improve condition and colour. FishBase notes the species feeding on small invertebrate foods such as worms, crustaceans and insects, so a varied diet is more natural than dry food alone.
Feed modest portions once or twice daily. They are quick midwater feeders, so make sure quieter bottom fish still receive their own food separately. Remove excess food and keep the water clean; hardy fish still suffer in tired water.
Choose robust, peaceful community fish that will not be intimidated by active tetras. Good matches include similar-sized tetras, rasboras, peaceful barbs, small peaceful lower-level companions, bristlenose plecos, dwarf cichlids in suitable layouts and other calm community fish. Avoid very tiny fish that may be bullied and avoid slow long-finned fish such as fancy guppies, bettas or long-fin angels, especially in smaller tanks.
They work well as an upper/midwater group above peaceful lower-level companions, but the listing itself is for Black Widow Tetras. The previous wrong bottom-dweller wording on this product has been removed from the visible copy.
Float the bag to match temperature, then acclimate gradually. Keep aquarium lights low during release and let the group settle before feeding heavily. A settled group should explore the middle water, school loosely and come forward for small foods within a few days.
During the first week, watch for fin-nipping, hiding or food competition. Most problems come from too few fish, cramped space, unsuitable long-finned tank mates or a tank that is not mature enough. Correcting the setup usually improves behaviour quickly.
Choose the size option that suits your aquarium and existing fish. Smaller sizes are useful for building a group that grows on together, while larger sizes give more immediate display. For the strongest result, buy enough fish for a proper shoal rather than keeping one or two individuals.
Once settled, Gymnocorymbus ternetzi is a reliable, high-contrast tetra for planted and mixed community aquariums. It is especially useful when you want a hardy schooling fish with a bolder shape than tiny nano tetras.
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