Almost every aquarist has enjoyed keeping at least one tetra species. For many of us, our first fish were tetras, with a common beginner’s choice being the neon tetra (Paracheirodon innesi). We were first attracted by tetras’ beauty, as well as the fact that most species are not demanding and are forgiving of rookie missteps.
After a while, though, aquarists tend to branch out. Thus, experienced fishkeepers often leave tetras behind and purchase more challenging or exotic fish. I think that seasoned aquarists should reconsider their dismissal of tetras and begin exploring a couple of species they might never have kept. I find the black skirt tetra (Gymnocorymbus ternetzi) and the Buenos Aires tetra (Hyphessobrycon anisitsi) to be particularly captivating.
Black Skirt Tetra
The black skirt tetra, also known as the black widow tetra or simply the black tetra (not the same as G. thayeri), comes from South America. Its native range includes the Paraguay and Guaporé rivers of Argentina, Bolivia and Brazil (Lima et al., 2003). This species is at home in these nations’ subtropical river basins, and it has also been introduced to Colombia and Thailand.
The average size of a black skirt tetra is about 2 to 2.5 inches. Its body is compressed and is semicircular in shape. The black skirt’s natural color is silver with black dorsal and anal fins. (Due to selective breeding, some fish exhibit a long-finned quality that gives them the general appearance of small angelfish.) Three dark vertical stripes are noticeable on each side of the body, with one of these running through the eye and the other two located behind the gills.
It’s not uncommon to find black skirt tetras that have been artificially dyed. The dyeing process can be detrimental to the fish’s health, and it often shortens the animal’s life span. All dyes eventually wear off, too, so these specimens should be avoided. Without dyes, expect to keep your black skirts for several years, as they are a naturally hardy species.
Black skirt tetras prefer to be kept in multiples. A single fish will become terrified, colorless and may even refuse to eat. It will die of loneliness if not provided with tankmates. Personally, I’ve found that a pair of black skirts will do well in a tranquil aquarium. Keeping more is certainly desirable, though, because the fish will form a shimmering shoal. An aquarium setup for this species should include plants, wood, rocks or some other structure. I find that mine greatly enjoy the shade of large leaves when the aquarium light is on. It is common to see these fish relaxing in the middle level of the tank, particularly near aquarium decorations.
Black Skirt Tetra at a Glance
Scientific name: Gymnocorymbus ternetzi
Size: 2 to 2.5 inches
Tank size: 10 gallons for a school of four
Water parameters: Temperatures in the mid-70s to about 80 degrees Fahrenheit, pH from 6 to 8, soft to moderately hard alkalinity levels.
Feeding: Staple flake foods. Make sure your black skirt tetras get enough to eat.
Breeding: Black skirt tetras scatter eggs on plants. Remove parents after eggs are laid, and eggs hatch in about 24 hours. Newborn fry need liquid foods; fry quickly graduate to ground flake foods, egg yolk and brine shrimp as they grow.
Notes: Keep them in groups.
They also seem to enjoy calmer waters than some other tetras. Water temperatures should be kept in the mid-70s to about 80 degrees Fahrenheit for black skirt tetras. As for water chemistry, I recommend a pH ranging from 6 to 8, with alkalinity levels from soft to moderately hard. These fish are not choosy about specific parameters. Great tankmates for black skirts include other tetras, rainbowfishes, cory (Corydoras spp.) catfishes and many species of freshwater shrimp and snails.
Feeding your black skirt tetras is not difficult. In nature, they eat insects, worms and crustaceans (Lima et al., 2003). Aquarists should offer them a staple diet of flake food with occasional treats to satisfy the fish’s dietary needs. They can be somewhat shy, though, especially around more aggressive eaters. I rarely see my fish feeding at the surface and have noticed that they prefer foods that sink slowly through the water column. Therefore, it is important that your black skirts are given the necessary opportunities to fill their stomachs when kept with more boisterous tankmates.
Black skirt tetras will breed in aquaria if separated from other species. Females are usually more plump than the males, which may have white spots on the anal fin. The male’s anal fin is also wider than that of the female. Spawning is most likely to occur in soft, slightly acidic water. The fish will scatter eggs on plants, but they provide no parental care. In fact, the parents are likely to eat the eggs, so remove the parents after spawning. The eggs will hatch in about a day, and the newborn fry can be fed liquid foods. Later on, switch them to ground flake food, egg yolk and brine shrimp (McEnery, 2009).
Buenos Aires Tetra
Like black skirt tetras, Buenos Aires tetras originate from South America. More specifically, these fish come from the Paraná and Uruguay river basins in the nations of Paraguay, Brazil and Argentina (Géry, 1977). And as implied by their name, these fish are common around the city of Buenos Aires. Fish of this species will commonly attain a size of 2.5 to 3 inches in captivity. This fish has a body built for speed and agility, and it is noticeably longer than the black skirt tetra. Also unlike the black skirt tetra, the Buenos Aires tetra displays bright hues. Their natural coloration is a silvery-green highlighted by orange finnage; albino Buenos Aires tetras are sometimes seen, too. A distinctive feature of the natural color form is the solid black marking located where the fish’s tail attaches to the body (the caudal peduncle).
The Buenos Aires tetra is a hardy fish. It can live for many years in the aquarium, and I’ve seen them recover from injuries and illnesses that would kill just about any other fish. These tetras do well when kept in schools, so try to buy four or more. Keeping a group of these highly active fish allows them to create a “pecking order” among themselves. This calms the Buenos Aires tetras and also benefits more passive community members. I have heard that some aquarists consider this fish to be a fin-nipper, but that has not been my experience. Still, the temperament of these fish best suits an aquarium with no overly sensitive fish.
Buenos Aires Tetra at a Glance
Scientific name: Hyphessobrycon anisitsi
Size: 2.5 to 3 inches
Tank size: 25 gallons for a school of five
Water parameters: Temperatures in the mid-70s to the low 80s, neutral pH and low to moderate hardness.
Feeding: Feed them bloodworms, water fleas, flakes and granules. Also include some vegetable matter in their diet.
Breeding: Buenos Aires tetras scatter eggs on plants. Remove parents after eggs are laid, and eggs hatch in about 24 hours. Newborn fry need liquid foods. The fry will soon move on to ground flake foods, egg yolk and brine shrimp as they grow.
Notes: Keep them in groups. Some may be fin-nippers.
While a small school of black skirt tetras would be fine in a 10-gallon aquarium, Buenos Aires tetras require more room (at least 25 gallons). I recommend adding them to a tank that is longer than it is tall. Such an aquarium offers plenty of exercise space. Tank decor can be similar to that used for the black skirt tetra, with one exception: Buenos Aires tetras will likely devour delicate aquatic plants. This species has a definite love for plant matter and should be expected to eat your live greenery. In my experience, Anubias and Java fern will generally be spared from destruction. My Buenos Aires tetras have rarely bothered these plants, except for occasionally chewing on the Anubias’ flowers. So, you can keep these fish with some live plants.
Buenos Aires tetras have no difficult care requirements. An unheated aquarium will suffice, but adding a little extra warmth will not harm the fish. Any temperature ranging from the mid-70s to the low 80s will be tolerated. As for water chemistry, these fish will thrive in waters harder and more alkaline than most tetras. They won’t mind hard water with a pH of 8. Still, I have found that water with a neutral pH and low to moderate hardness is the best for this species.
Feeding Buenos Aires tetras is simple: Drop food in, wait a second, watch it disappear and repeat a few more times. This species will attack bloodworms, water fleas, flakes and granules. If something will fit in their mouths, they will devour it. Due to this fish’s herbivorous streak, include some vegetable matter in their diet. The most entertaining way to do so involves a common salad item: Try cutting a slice of raw cucumber and dropping it into your aquarium. It should float around and offer a target for your fish. Alternatively, you can anchor cucumber to the bottom with a small weight (a metal shower curtain ring works nicely). Buenos Aires tetras will eat their way through the cucumber, leaving only the skin and seeds behind.
Buenos Aires males are slimmer than females. Males also display brighter colors on their fins (Brough, 2009). Creating ideal spawning conditions for Buenos Aires tetras requires essentially the same setup I described for the black skirts. Many characins breed in the same manner and don’t require unique setups. Fry of this species can also be cared for using the methods described earlier.
Tetras are a diverse group of fish, and it would be difficult to become well-acquainted with all of the tetras commonly seen in the aquarium trade. The two species I’ve described here just might be fish you’ve overlooked. Although other tetras may be more popular, black skirt and Buenos Aires tetras both make enjoyable additions to the community tank. These species are excellent choices for beginners and experts alike. So, consider a new tetra species (or two) for your tank! FAMA
Nathan Yates has maintained aquariums for more than 15 years. He is especially interested in the care of freshwater invertebrates, aquatic plants and rainbowfishes.