Tetras are freshwater tropical fish that include both small South American fish belonging to the family Characidae and African fish belonging to the family Alestiidae. There are numerous species that are referred to as tetras, including the very popular neon and cardinal tetras. Other popular types include rasbora tetras, black skirt tetras, and head-and-tail light tetras. They are hardy and make good aquarium inhabitants if kept in schools.
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1. Cardinal tetra
- Scientific Name: Paracheirodon axelrodi
- Family: Characidae
- Size: 1½ inches
- Temperature: 75 to 82 degrees Fahrenheit
- Alkalinity: as soft and acid as possible
- pH: 6.0 to 6.8
- Origin: Upper Rio Negro and Amazon basins
The cardinal tetra is probably the world’s favorite tropical fish in terms of numbers kept. Many hobbyists have at some point in time, kept cardinal tetras. And, while they have been bred, they have never been bred in commercial quantities. Therefore, millions of cardinals are caught wild and exported from Brazil every year. Dr. Labbish Chao has started a program called Project Piaba (piaba is the native name for little fish that swim with cardinals) to help educate collectors/exporters and improve the conditions under which the fish from Brazil are caught, conditioned, and shipped to the world. Even though millions of cardinal tetras are caught every year, the fishery is managed very well. The fish are not allowed to be caught during the breeding season or shortly thereafter, and the Amazon/Rio Negro area is so vast that fishermen do not go back to the same site for years, thus allowing the cardinals to replenish.
Keeping a cardinal in the home aquarium is very easy as long as two conditions are met. First, do not keep it with larger fish (such as angelfish or other large cichlids) that quite naturally look upon the cardinal as food. And second, the cardinal needs soft, acid water. Water may be adjusted by using reverse osmosis or deionized water or putting a peat pillow into the filter. Once the pH starts getting above 6.8 and/or the hardness above 12 DH, the cardinal doesn’t do well.
When given the water conditions it likes and kept in a tank without any predators, the cardinal will do spectacularly well. It will eat absolutely any food: flake, frozen, freeze-dried or live. It does not bother its tankmates. Like all schooling fish, the cardinal is best kept in groups of at least six or eight, and more if possible.
2. Neon Tetra
- Scientific Name: Paracheirodon innesi
- Family: Characidae
- Size: 1¼ inches
- Temperature: 76 to 82 degrees Fahrenheit
- Alkalinity: Acidic and soft
- pH: 6.2 to 6.8
- Origin: Amazon basin (headwaters)
The neon tetra was the first wild-caught fish that really set the tropical fish hobby into a dither, and contributed much to establishing the “tropical” fish hobby. When the neon was first introduced in Europe and then America, this fish commanded incredibly steep prices. Now that it is produced in huge quantities in the Far East the fish is a common staple and always available.
The ideal water condition for the neon tetra would be rainwater — pH around 5.5 to 6.2 and a virtually immeasurable hardness. Fortunately, because almost all neons in the local fish stores are commercially raised, they can take higher readings for both pH and hardness, although anything above 7.2 and 12 to 14 DH is less than ideal for these little gems. Keep them in good-sized schools, at least 10 to 15 fish and preferably more, and give them plenty of thickets of plants to hide in.
Breeding the neon tetra requires clean water with a pH no higher than 6.5 and with as little hardness as possible. Both the breeders and the eggs are sensitive to bright light, so it is best to keep only a dim light on the tank for breeding, and after the fish have spawned the tank should be covered with a blanket or the like to make it totally dark. After two days of darkness use a flashlight to look for any newly hatched babies, which look like tiny glass splinters. For the first two weeks of their life the babies should not be exposed to any bright light.
Although this fish appreciates live or frozen foods, especially when being conditioned for spawning, the neon tetra will do very well on just flake foods. Make sure this fish gets enough to eat if housed in a community tank, as the neon tetra is not very aggressive about feeding.
3. Black Skirt Tetra
- Scientific Name: Gymnocorymbus ternetzi
- Family: Characidae
- Size: 1½ inches
- Temperature: 70 to 76 degrees Fahrenheit
- Alkalinity: soft and acid, to neutral
- pH: 6.4 to 7.0
- Origin: Rio Negro basin
The black tetra has been a popular staple of the aquarium hobby for many years. Commercial breeders have developed different color varieties (unfortunately, including the “blueberry” and other dyed fish), and there are long-finned specimens. The black tetra has been bred in such quantities both in Florida and the Far East that fish imported from the wild are virtually never seen.
An ideal community tank fish, the black tetra does best in schools of at least five or six fish, and it prefers a planted tank with plenty of places for it to hide and hang out in. It will eat absolutely anything in the way of the standard aquarium fare, and can even be conditioned for breeding on dry food. One could not ask for a more pleasing fish to keep.
4. Lemon Tetra
- Scientific Name: Hyphessobrycon pulchripinnis
- Family: Characidae
- Size: 2 inches
- Temperature: 72 to 78 degrees Fahrenheit
- Alkalinity: Slightly soft and slightly acidic
- pH: 6.8 to 7.0
- Origin: Amazon basin
The lemon tetra is not seen much in the hobby anymore, most probably because when young, the fish does not show much in the way of colors. Also, the commercial breeding of this fish in Florida and the Far East has taken what was already a very subtle range of colors and made them even less notable.
An excellent community tank fish, the lemon tetra really has no drawbacks. This fish will eat any foods — flake, frozen or freeze-dried — and is happy in water that is around neutral with moderate hardness. Like any other tetras from the Amazon, the lemon tetra does best in water that is slightly acid and relatively soft. When kept in a community tank, this fish tends to display better and seems more comfortable if kept in schools of at least six or eight fish. And, like the glowlight and other tetras in which the body is almost transparent, the lemon tetra shows best if its tank has dark, or black, gravel.
Breeding is not a problem, although the lemon tetra has a reputation for being an egg eater. It’s best to spawn this fish only in pairs because there will be fewer adult fish to eat the eggs than if the fish was bred in groups like many other tetras.
5. Bleeding Heart Tetra
- Scientific Name: Hyphessobrycon erythrostigma
- Family: Characidae
- Size: 3½inches;
- Temperature: 72 to 82 degrees Fahrenheit
- Alkalinity: not particular
- Origin: Upper Amazon Basin, Peru
The bleeding heart tetra is a hardy, peaceful, schooling species that should be kept in groups of six or more. It does extremely well when kept with other peaceful fish, such as Megalamphodus, Corydoras and Nannostomus species.
The bleeding heart tetra prefers a somewhat dark environment. It is best housed in a tank that contains several bunches of large plants (either live or plastic) in the back and on the sides of the tank, with smaller plants in the front, leaving plenty of open space for swimming. A layer of floating plants to diffuse the light is also suggested. Pay strict attention to water quality.
Most tetras are carnivores that are specialized for eating small aquatic insects and the larvae of terrestrial insects. In the aquarium, the tetra will do quite well on commercial flake, frozen or freeze-dried foods. Be sure to vary its diet between dry foods and small live foods, such as bloodworms, glass worms, brine shrimp and Tubifex worms.
The bleeding heart tetra is a typical egg-scattering tetra that requires a larger-than-normal breeding aquarium (20 gallons or larger) to successfully mate. It can be sexed by the extended dorsal and anal fins and brighter colors of the male, but it is still best to buy a group and let them pair off because the tetra seems to breed more readily when it can choose its mates.
6. Buenos Aires Tetra
- Scientific Name: Hyphessobrycon anisitsi, formerly Hemigrammus caudovittatus
- Family: Characidae
- Size: 3½inches;
- Temperature: 65 to 82 degrees Fahrenheit
- Alkalinity: neutral to slightly alkaline with moderate hardness
- pH: 6.8 to 7.4
- Origin: Argentina
The Buenos Aires Tetra is now provided to the hobby almost exclusively from fish farms in Florida, which means it usually has been raised in alkaline, hard water. It will, however, adapt back to its original conditions of neutral soft water. In fact, the Buenos Aires Tetra is one of the most adaptable fish in the hobby. It does well in almost any water condition in terms of pH, hardness, and temperature.
Two things to be noted about the Buenos Aires tetra are that when it gets large and older it tends to be somewhat aggressive and is a fin nipper. It will eat plants with a vengeance. Other than this, it is a fine community tank fish. It will eat any and all kinds of fish food with great gusto.
Breeding the Buenos Aires tetra is very easy. It spawns in typical tetra fashion, dropping somewhat adhesive eggs into thickets of plants or artificial spawning mops. It is very active when spawning, so it should be given as large a tank as possible for this purpose.
7. Diamond Tetra
- Scientific Name: Moenkhausia pittieri
- Family: Characidae
- Size: males to 2%frac12 inches, females smaller
- Temperature: 72 to 80 degrees Fahrenheit
- Alkalinity: acid side of neutral, moderately soft
- pH: 6.6 to 7.0
- Origin: Venezuela (Lake Valencia)
The diamond tetra’s lack of color is more than made up for by its other attributes. The scales located on the sides of this fish are reflective and almost shimmer. Its overall color is a glittering silver with highlights of greenish-blue. Mature males have an elongated dorsal fin, which, when fully developed, trails almost to the tail. This fish does best in a school of at least six or eight fish, where one male will become dominant, tolerating other males but reminding them of their place behind him.
An easy fish to keep, the diamond tetra requires water on the acid side of neutral, with only moderate hardness. However, it will adjust to a slightly higher pH and hardness, although it may not look its best in those conditions. It can be kept with any other community fish, and it enjoys a heavily planted aquarium. Feeding is not a problem because it will take any standard fare, be it flakes, frozen or freeze-dried. It relishes, of course, any live food offered to it.
The diamond tetra is very easy to breed, and many aquarists find baby “survivors” showing up in their community tanks, especially if there are plenty of plants for the babies to hide in. The diamond tetra can also be set up for breeding separately, treat it just like any other tetra.
8. Glowlight Tetra
- Scientific Name: Hemigrammus erythrozonus
- Family: Characidae
- Size: 1½ inches
- Temperature: 72 to 78 degrees Fahrenheit
- Alkalinity: Slightly acidic and moderately soft
- pH: 6.6 to 7.0
- Origin: Guyana
The glowlight tetra is one of the most beautiful and easy to keep fish offered in our hobby. If you want an absolutely spectacular tank, put a school of glowlights in with black gravel, lots of plants and subdued lighting. You will understand the “glow” part of their name. They look almost unearthly, like some form of phosphorescent orange/red lines surrounded by fish.
The glowlight need slightly acid water with moderate hardness, but it is very sensitive to nitrate and nitrite, so this fish should be kept in a tank that has active and complete biological filtration. If the water quality is not to the fish’s liking it will not show to its best advantage, and can, in fact, become almost colorless. Water changes and plants will keep this fish happiest.
The glowlight tetra accepts all foods — flake and frozen — and is always a greedy eater. Spawning is in the typical tetra fashion, although the glowlight tetra has a habit of turning completely upside down when spawning. The eggs, as with neons and cardinals, are very sensitive to light, so once the parents have spawned, the tank should be kept in the dark for two days until the eggs actually hatch out.
9. Blind Cave Tetra
- Scientific Name: Astyanax fasciatus mexicanus
- Family: Characidae
- Size: 3½inches;
- Temperature: 65 to 78 degrees Fahrenheit
- Alkalinity: undemanding
- Origin: Mexico, Texas
The blind cave tetra is a schooling species that is a little too aggressive for the normal tetra community. It is best kept in a group of three to six individuals in a tank with other robust fish, such as small cichlids, livebearers, barbs and catfish.
Like most tetras, the blind cave tetra prefers a somewhat dark environment. It is best housed in a tank that contains several bunches of large plants (either live or plastic) in the back and on the sides of the tank, with smaller plants in the front, leaving plenty of open space for swimming. A layer of floating plants to diffuse the light is also suggested.
Most tetras are carnivores that are specialized for eating small aquatic insects and the larvae of terrestrial insects. In the aquarium, the blind cave tetra will do quite well on commercial flake, frozen or freeze-dried foods. Be sure to vary its diet between dry foods and small live foods, such as bloodworms, glass worms, brine shrimp and Tubifex worms.
As with most tetras, the blind cave tetra is an extremely prolific breeder, and, although the adult female appears to have a fuller body, the best way to ensure a breeding pair is to purchase a group of six or more and let them pair up. The fry hatch quickly — within two to three days — and are free-swimming from the sixth day. The fish are able when fry, but as adults, they lose their eyes.
10. Head and Tail Tetra
- Scientific Name: Hemigrammus ocellifer
- Family: Characidae
- Size: 2 inches
- Temperature: 72 to 80 degree Fahrenheit
- Alkalinity: Neutral to acidic, moderately soft
- pH: 6.6 to 7.0
- Origin: Amazon drainage of South America
