Black Skirt Tetra care guide
Black Skirt Tetra (Gymnocorymbus ternetzi) — minimum tank 60 L, temperature 22-26 °C, pH 6-7.5.
Compiled by Aquairi from published sources · Published · Updated
Overview
The Black Skirt Tetra (Gymnocorymbus ternetzi) is a robust characid from the Paraguay and lower Guaporé river basins of South America. Adults are recognised by their compressed silvery body and large dark anal and dorsal fins that fade with age. Several selectively bred colour and long-finned forms are widely available in the aquarium trade.
Taxonomy
- Family: Characidae
- Genus: Gymnocorymbus
- Scientific name: Gymnocorymbus ternetzi
- Common synonyms: Black Widow Tetra
Habitat
Wild populations inhabit slow-moving tributaries, oxbow lakes and flooded margins of the Paraguay, Paraná and lower Guaporé river systems in Brazil, Paraguay, Bolivia and northern Argentina. The species is typically found among aquatic plants and submerged roots in clear to slightly turbid water.
Tank requirements
- Minimum tank volume: 60 L (15.9 US gal)
- Adult size: 5-7 cm
- Temperature: 22-26 °C (72-79 °F)
- pH: 6-7.5
- GH: 3-15 °dGH
- Water flow: low
- Lifespan: 3-5 years
- School size: ≥6 individuals
Diet
A generalist omnivore. In nature it consumes small crustaceans, insect larvae and plant matter from the water column. In aquaria a varied diet of quality flakes, micro-pellets and regular live or frozen foods (daphnia, bloodworms, brine shrimp) maintains colour and condition; feed twice daily in small portions.
Compatibility
A peaceful mid-water schooling fish that becomes fin-nippy if kept singly or in groups below six. Keep a shoal of at least six and avoid pairing with long-finned slow species (Betta, fancy guppies, Angelfish in small tanks). Suitable tankmates include other robust tetras, Corydoras and Bristlenose Pleco.
Breeding
An egg-scatterer. Conditioned pairs spawn over fine-leaved plants or a spawning mop; adults should be removed after spawning as they readily consume the eggs. Fry hatch within roughly 24-36 hours and accept infusoria followed by newly hatched brine shrimp.
Conservation status
IUCN Red List: not assessed for this species; populations are abundant and most aquarium stock is commercially captive-bred.
GloFish Black Skirt Tetra Breeding Guide
Overview
The GloFish Black Skirt Tetra is a genetically modified Black Skirt Tetra, Gymnocorymbus ternetzi, that carries a fluorescent-protein gene; its spawning biology is that of the wild black skirt tetra, an egg-scattering characid that gives no parental care. The fluorescent colour is a heritable transgenic trait, and GloFish is a registered trademark; in many jurisdictions the propagation and sale of these trademarked transgenic fish is restricted, so hobby breeding may be subject to legal limits.
Sexing
In the black skirt tetra, males are noticeably slimmer and a little smaller than females, and the male also has more pointed dorsal and anal fins than the female.
Conditioning
Condition the sexes separately on plenty of live and frozen foods at around 24-26 C (75-78 F) before attempting to breed.
Breeding Setup
- Spawning tank around 18 x 12 x 12 inches (about 45 x 30 x 30 cm), dimly lit.
- Temperature raised to about 28-30 C (82-86 F), several degrees above the main tank.
- pH on the acidic side of neutral.
- Clumps of fine-leaved plants such as java moss or spawning mops, or a mesh base that lets eggs fall out of reach of the adults.
Spawning Behavior & Trigger
Spawning can occur in a group of about six males and six females or as a pair. In pair spawning the fish typically spawn the morning after being transferred. Eggs are scattered among the plants or fall through the mesh, and the adults will eat the eggs, so they should be removed immediately on detection.
Egg & Fry Care
Eggs hatch in around 18-36 hours and the fry are free-swimming a few days later. Eggs and fry are light sensitive in the early stages and need dim lighting. First food is an infusoria-type food, progressing to microworm and brine shrimp nauplii.
Common Challenges
Besides the usual egg predation and light sensitivity, the trademarked transgenic status is the key consideration: fluorescence is inherited, but propagating GloFish may be legally restricted, and offspring colour and any selectively bred finnage are heritable rather than fixed.