GYMNOCORYMBUS TERETZI – BLACK TETRA (AKA – BLACK SKIRT TETRA, BLACK WIDOW TETRA, BLACKAMOOR, BUTTERFLY TETRA AND PETTICOAT TETRA)
The commonly called Black Skirt Tetra comes from South America – Paraguay, Brazil and Bolivia – the drainage basins of the Amazon, Rio Paraguay, Rio Pilcomayo, Rio Guapore, Rio Mamore, Rio Beni, Rio Madeira, Rio Tapajos, Rio Negro and Lake Rogoa, in shaded, mostly shallow waters and flood regions.
You must see this fish to realize its remarkable beauty. There are many very good reasons why this fish has been so popular since its introduction to the aquarium would in the 1930’s. The Black Tetra was so popular in fact it garnered, not one, but at least 6 popular common names over the years. Not only is this a fish of striking colors, it has a unique shape and is one of the least demanding fish to keep in the home aquarium. Can stand ranges of temperatures from 60F to 90F, eats anything, is non-aggressive and breeds very easily!
The physical description of this fish does not do it justice. First, the rear half of the body, the large dorsal fin, and the exceedingly large anal fin are jet black. The forward part of the body is silver with clearly visible vertical black bars. The caudal fin is clear, that is to say transparent. The anal fin is so large that the fish appears to wear a ballet skirt and it certainly seems to dance, as it hovers around the darker areas of the aquarium! To add to the Black Tetra’s unique appearance, it has silver-rimmed jet black eyes.
In its native habitat in Paraguay and the Matto Grosso area of Brazil, the Black Tetra grows to a length of three inches, although in captivity it seldom grows to more than two inches. An interesting feature of this characin is that with fright its colors turn pale. From its habitat we could expect the Black Tetra to endure a wide range of variations in temperature; however it thrives at anything from 70F to 85F. It is best to breed this fish at about 75F. The Black Tetra is a very active fish and indulges in much harmless chasing of other fish, though it never seems to injure them.
This species was first introduced to fish keepers in 1935 from just 3 of the species that had been imported from the Amazon basin; for many years, all the Black Tetras being kept in aquariums were descendants of this original trio! As their domestication proceeded, they developed into one of the easiest egg-layers to breed in the aquarium world. One reason is that this is a very widely bred fish in farms, and its collection in the wild proved to be far more expensive than breeding this extremely prolific fish in Florida.
One pair of Gymnocorymbus Ternetzi in prime breeding condition can produce 500 offspring every 2 to 3 weeks! More over, they can do this through the temperature fluctuations in the Florida environment. Finally, inbreeding is not a problem with this species, and after nearly 70 years of inbreeding, this species natural reproduction is in captivity.
Another strain of this species has been developed over the years, the long-finned variety. There are many strains of this variety, look for a pair that has very long free flowing fins, with no kinks or small bumps, for best resulting fry. The long-fin variety breeds true for the most part.
Like many Characins, Black Tetras require a large aquarium of at least 10 gallons, clear water, and a thick growth of plants along the walls, leaving plenty of swimming space in the middle. The darker the background and bottom of the tank, the more at ease the fish feels, the brighter the colors and the more eggs they will be comfortable laying!
Many aquarists find it difficult to sex half-grown specimens. But if the eye is trained to observe only the body of the fish, and to disregard completely the fins, it will be easy to see that the males are more elongated and the females are deeper in comparison with their length. When in prime breeding condition, the female Black Tetra will look as if she is latterly about to explode, and the sex difference is more than obvious at this point, as she can be filled with up to 1,000 eggs, which are large by Characin standards!
The male Black Tetra are somewhat smaller than the females, with small white tips on the tail fin. In transmitted light, like a strong flashlight from behind the fish, you can see that the translucent body cavity of the male run into a point towards the rear, but the female is rounded in the rear. The fins also provide a means of separating the sexes; the male’s dorsal fin is more pointed than that of the female and the males anal fin is broader at the front.
Black Tetras can be breed with great success by the novice, and are considered ideal for a home breeding project. Successful Black Tetra breeders are usually 9 months to a year old, and from 1 ½ to 2 inches long. Weather breeding the long-fined variety, or the standard (usually the best bet for the beginner), the female should be conditioned separately from the male for 7-10 days on a steady diet of 3 live or frozen brine shrimp, blood worm and misquote larva diet meals per day.
Tank should be filled with at least 4 or 5 fine leaved bunches of plants, leaving large open areas, these fish like to swim and chaise fast! Introduce the female in the late afternoon, followed by the male one hour later, just before dark. They will breed the next morning, the male Black Tetra chasseing the female through the plants and occasionally quivering, laying up to 500 or even 1000 eggs over 2 or 3 hours. When the chase stops, they will rest a few minutes and then start searching for and eating eggs. Both parents should be removed at once. There are so many eggs, that as long as you stop the egg hunt within an hour or so you will have many eggs left.
You should use aged but virgin water, making sure all plants are washed in a salt bath to kill any snails and other pests that will eat the eggs. PH and hardness are not critical, but ideally 6.8-7.0 and a hardness of 100-150 ppm. The temperature should be raised to about 75F-78F. The water should be heavily aerated before introduction of the pair, and then left totally still until the fry are free swimming.
The eggs hatch after about 24-36 hours. They hop on the bottom, or cling to the glass like little slivers for another 2 to 3 days, when they become free swimming and immediately begin swimming and darting about in constant surch for food. Unlike most Characins, the Black Tetra is immediately able to swallow good sized pieces of food, this results in very rapid growth if fed frequently. A sponge filter should be added at this point. Because of their great number, enough usually survive, even for the novice, that they may have be divided to several tanks for maximum growth.
First week of free swimming, the Black Tetra should be fed infusoria and first bit powered food, the second week start baby brine in the mix and the third week graduate to growth food and baby brine shrimp. The critical period is the first 2 weeks from the time they are free swimming. During this time temperature should be a constant 75F to 78F and water should not be touched.
After two weeks 10% water changes, siphoning off the uneaten food from the bottom is recommended by weekly. At this point the Black Tetra fry are well on their way and will eat almost anything. The Black Tetra are really most beautiful in their first 3 months when they are almost completely black, they begin to look like adults in about three months and mature at about 6 months.
Try this breading project and send us some pictures to post of your success with the Black Tetra, and remember, its a hobby, enjoy every project. In order to be most successful, make sure to treat the fish in a humane manor and work hard to do your best to support the life and lives you are dealing with!
Enjoy – Dr. Reich