From electric blue neons to bright red embers, tetras are some of the most beautiful species to stock in your nano tank. This family of fishes exhibits a diverse array of colors and patterns, turning even the smallest of home aquariums into a stunning showcase.
In this guide, we’ll explore the wondrous world of tetras to discover things like where do Tetras come from, which species are best for nano tanks, and how to help them thrive in your own aquarium.
Tetra Fish Diversity and Distribution
The common name tetra applies to small freshwater fish belonging to the family Characidae. The term was originally shortened from Tetragonopterus, a genus of characids. Now, however, the name tetra isn’t exclusively taxonomical—many species within the family Characidae are commonly known as tetras.
Tetra fish are primarily found in Africa, Central America, and South America. They’re generally small with compressed bodies and often fusiform in shape. The term fusiform refers to a spindle-like shape where the body is round in the center and tapered toward the ends (the nose and tail). What distinguishes tetras from other families of fish is that each has a small adipose fin on the underside of the body, positioned between the dorsal and caudal fin.
While tetras are found on several continents, a majority of species can be found in the river systems of South America—primarily the Amazon River Basin. Tetras typically inhabit slow-moving creeks, streams, and rivers where the water is clean and warm. Their native habitats tend to be densely planted with soft soil or sandy substrate.
Popular Nano Tank Tetras
There are hundreds of different species of tetra, many of which are appropriately sized for nano tanks. The thing to keep in mind is that tetras are schooling or shoaling fish, so they’re best kept in groups of their own kind. It’s important to choose a tank large enough to accommodate at least six of your chosen tetra species.
Let’s explore some of the most popular nano tank tetra species from different regions of the world.
African Tetras
Over 100 species of tetra are found exclusively in Africa, all of which belong to the family Alestidae. Some of the best species for nano tanks include:
- Congo Tetra (Phenacogrammus interruptus) – These full-bodied tetras exhibit a range of iridescent hues including blue, red, and yellow-gold. They grow up to 3 inches and, as they mature, develop a feathery appendage on the tail fin.
- African Moon Tetra (Bathyaethiops caudomaculatus) – Native to the central and lower Congo River basin, this deep-bodied tetra is gold in color with a large black spot at the base of the tail and a small red spot under the dorsal fin.
- Jellybean Tetra (Ladigesia roloffi) – Also known as the Sierra Leone dwarf characin, this species grows to a maximum of 1.5 inches. Jellybean tetras have iridescent green bodies and bright orange fins.
Central American Tetras
While most tetras are found in South America, some species can also be found in Central America. The most popular Central American species, however, is the Mexican tetra or the blind cave tetra (Astyanax mexicanus). Reaching an adult length around 4 inches, Mexican tetras are best kept in groups of 5-6 in a 20–30-gallon tank. Because these fish do not have eyes, they favor dimly lit aquariums.
South American Tetras
Some of the most popular tetra species are native to South America including the neon tetra (Paracheirodon innesi) and its look-alike the cardinal tetra (Paracheirodon axelrodi). Other South American tetras that are particularly appropriate for nano tanks include:
- Ember Tetra (Hyphessobrycon amandae) – These tetras exhibit striking orange to reddish all-over coloration that turns translucent toward the tail. They grow to about 1 inch in length.
- Lemon Tetra (Hyphessobrycon puchiripinnis) – Growing to a maximum of 2 inches in length, the lemon tetra is a deep-bodied nano fish known for its translucent yellow body and vibrant yellow-and-black fins.
- Green Neon Tetra (Paracheirodon simulans) – Similar in appearance to the neon tetra, this species is a little larger and has a distinctly green body color along with the characteristic red patches.
- Penguin Tetra (Thayeria boehlkei) – Also known as the blackline penguinfish, penguin tetras are silver-gray in color with a thick black line running laterally along the body through the lower lobe of the tail.
- Redeye Tetra (Moenkhausia sanctaefilomenae) – These tetras have bright silver bodies, half-black tails, and thin red circles around the eyes. They grow up to 2 ¾ inches in length.
Tips for Keeping Tetras in Nano Tanks
Most of the tetras sold in the aquarium trade are tank-bred, which means they’re generally fairly hardy and adaptable to various conditions. Like any aquarium fish, however, tetras are most likely to thrive in a stable tank environment that mimics their native habitat.
Here are some features to incorporate into your tetra nano tank:
- Clean, slow-moving water with high oxygen levels. Gentle filtration with a mild but steady flow is ideal—avoid anything that creates too strong a current.
- Low level of hardness. Though individual species’ preferences depending on their origins, tetras generally prefer soft water up to 10-15 degrees of hardness (dkH).
- Plenty of live plants and natural décor elements. Live plants help oxygenate the water and provide cover for tetras but make sure there’s still plenty of open swimming space.
- The tight-fitting lid on the tank. Most tetras don’t jump for no reason but if the school gets spooked by something, they may jump out of fear.
- Small, peaceful tankmates. Tetras generally get along well with other small, peaceful species, including bottom-dwellers like Corydoras.
- Weekly water tests and regular water changes. Maintaining a stable tank environment is key, so test your water chemistry regularly and perform water changes as needed.
To keep your tetras healthy, offer a varied diet of small, high-quality foods. Tetra species are largely omnivorous and tank-bred specimens usually accept small commercial foods. Supplement a commercial staple diet of pellets, granules, or flakes with small live, frozen, and freeze-dried foods.
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