Black tetra (lat. Gymnocorymbus ternetzi) — is a kind of freshwater fishes of the Characidae family. It inhabits in the rivers of Mato Grosso, Paraguay and Rio-Negro. This kind of fish has easily adapted to aquarium conditions, it breeds easily and has a numerous offspring. However, this fish may start nipping other fishes fins, so it’s not a good idea to keep it in a tank with veiled kinds of fishes or with long-finned ones.
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Habitat in the wild
The black tetra was first described in 1895 by Boulenger, and then it was brought to Europe in 1933. A model fish species when scientists created glofish tetra.
In the wild habitats are in Mato Grosso, Paraguay and Rio-Negro rivers. However, they have adapted to tank conditions quite well and now the fish is widely spread in aquariums. Tetra prefers slow waters of small rivers, streams, tributaries well shaded by the tree branches. Nowadays the fish is almost not exported, since the majority of them is bred at farms.
| Scientific Name | Gymnocorymbus ternetzi |
| Family | Characidae |
| Common Names | Black tetra; black skirt tetra; striped tetra |
| Range and habitat | South America |
| Size | 7.5 cm (3.0 in) |
| Lifespan | 4 years |
| Ease of keeping | Easy |
| Minimum tank size | 80 liters (20 gallons) and more |
| Temperament | Peaceful |
| Diet | Omnivorous |
| Temperature | 21–27 °C (70–81 °F) |
| pH | 6.5-7.5 |
| Water hardness | 5-20 dGH |
Description
Black tetra has high and flattened body. It grows to be 4.5 cm long and starts breeding just being 7.5 cm (3.0 in) long. Lifespan is about 4-5 years provided with good tank conditions. The body is laterally flattened, it has dark-silvery coloring with three vertical black stripes.
One of them crosses the eye, the second one starts at the opercles endings. The remaining part of the body starting from the third stripe, including upper and proctal fins, is black and it looks like a skirt.
The pectoral, dorsal and pelvic fins are quite transparent, and its proctal fin reminds a black skirt, as we’ve mentioned earlier. Is rather energetic and active fish, it swims in schools and they often attack each other.
The black tetra has another color morphs: the long-fin black skirt tetra that was first bred in Europe. It can be very often seen on sale and it has nothing different in care comparing with the classical tetra, but it’s a bit more difficult to be bred due to inbreeding.
As for the albino black tetra variation a – they are encountered more seldom, but they differ from the black skirt tetra only in color.
Glofish tetra – these are genetically modified (GMO) fishes. This is a modern and very popular trend in aquarium husbandry nowadays. However, you should buy such fishes sensibly, keeping in mind that GMO have never made anyone healthier and these fishes lifespan maybe shorter due to this.
Difficulties in keeping
Care is undemanding and this is a fish for beginner. It adapts well and it eats any kind of feed. The fish is good for community tanks at the condition that it won’t have long-finned tank mates.
Care and keeping in a tank
Since black skirt tetra is a very active one, it has to be kept in spacious tanks from 15 gallons capacity. The fish likes soft and acidic water with fluctuants and not bright light. Don’t forget to close your tank, because the fish can jump pretty well and it can die outside.
This kind of fish perfectly appears in a tank with natural biotope – sandy bottom, number of snags and fallen leaves on it, which make the tank water brownish and acidic. Tank maintenance is a standard one and the same as for all other fishes. Weekly water renew up to 25% from the total water amount and a filter are common requirements.
Water parameters may be different, but these are the most preferable ones: temperature 21–27 °C (70–81 °F), pH: 6.5-7.5, 5 – 20 dGH.
Feeding
Black tetra is completely not demanding as for the feed, so any kind of live, frozen or artificial feed will do. The fish prefers flakes and other types of feed that stay on the water surface.
Tank mates
Due to its peaceful temperament tetra can be kept in a tank together with other small Characins. The black tetra is ideal for mixed aquarium. Fish must be kept in schools, since when it’s all alone it becomes aggressive. It’s better not to keep it together with smaller fishes or long-finned ones.
Because they will bite the latter, for example, don’t keep it with bettas or angelfish. Cardinal tetra, neon tetra , black neon tetra, tiger barb and other not large and active fishes will be good tank mates for that fish.
Gender differences: male vs female
Black tetra males have longer and more sharpened fin, at that the female is fatter and the black skirt on its proctal fin is significantly wider.
Breeding
Is an egg-laying fish and suitable spawning temperature for it is — 25-27 °C, water hardness 4°, pH 6.5-7.0.
Breeding occurs between the black tetra couples (sometimes it happens in a school). First, male is put into a spawning tank and then it a few hours – the female. Next day in the morning you should light the tank very brightly – this will push the spawning.
The light may be both natural and artificial. The spawning tank should have its bottom square equal to about 1500 cm² (50×30 сm) with some Java moss or a caproic net put on its bottom.
The net should have its cells wide enough for the falling fish eggs to get through and at the same time – not too large – to prevent fish from eating them. A couple can lay up to 500 and sometimes 1000 eggs during one spawning. After it is finished the fishes are removed from the spawning tank. The eggs incubation time is 24-36 hours, then larva appear and in 3-5 days they turn into juveniles, start to swim and feed.
The start feed for them is – infusorians and rotifers. Less of the juveniles survive if you feed them with some artificial feed. Also, while juveniles grow, they should be sorted and put into different tanks according to their size to prevent cannibalism among them.