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Characiformes Introduction 

Jaws-toothed fish are always a remarkable excitement for aquarists. Among those families, It always come as one of the top options among aquarium hobbyists.

With almost 2000 different species, you can have a robust and unique appearance from Characiformes fish. Breeding and maintaining Characiformes could be challenging but the effort.

It is an exotic freshwater fish family that refers to thousands of different species found in Africa and most parts of America(north, central, and south). 

These fish can survive and grow in 20-gallon  tanks with specific care and warmer water. It can refer to those piranhas and tetras that are happier with larger schools in the environment(aquarium).


Category Rating
Level of care Medium-Hard
Temperament Peaceful. Some species are fiercer
Appearance Regardless of the species, the fish always has a ray fin in the back.
Life expectancy 1-9 years
Size 1.5 – 12 inch
Diet Carnivores. Some species are omnivores 
Family Characidae
Tank size 10 – 20 gallon or larger
Tank environment It can survive in a small range of water parameters with the substrate, robust plants, and larger swimming space. 
Tank Mates A group of six

Other species with the same diet


Characiformes About

This or the Characins are ray-finned fish that refers to the back adipose fin situated between the tail and dorsal fin.

These fish are native to the tropical regions including Africa, part of North America, Central America, and of course, South America.

In the Aquarium industry, the popular Characiformes fish are those Tetras originated throughout the Great River Amazon.

They’re simply the tropical fish that live in the rivers, streams, ponds and lakes with an acidic but soft water environment and a small range of water temperature(28 C to 30 C).

It cover at least five families that give you thousands of species under its name.

These cover the smallest fish Paracheirodon innesi that’s only 5cm long to the largest one Rooseveltiella nattereri or renowned as the Red Belly Piranha that can go up to 30cm long. While they have different sizes, all of them share the same characteristic: that ray fin.

When it comes to the aquarium environment, some names have gained popularity among aquarists. Taking care of Characiformes fish could be challenging and not all species are recommended for domestication as they require professional handling.

Tetras could have been the most popular species of the Characin family that currently live in the aquarium.

The main attractions of this fish, especially the tetras, include their eye-catching coloring and schooling behavior.

They’d swim around your tank instead of being territorial in the aquarium that makes them enjoyable to watch. Each Characiformes species is distinctive and has attractive colors.

Characiformes Types/Species

There are up to 2000 species of Characiformes but they can be reduced to hundreds referring to their readiness for an aquarium environment.

Some exotic Characiformes species aren’t recommended for beginner aquarists since they may require specific handling, tools, and tank setup.

  • Tetras

Tetras are the most popular group of ray-finned species that thrive in aquarium environments. However, not all tetras are eligible for tank hobbyists, only some of them can be domesticated in the controlled aquarium environment.

  • Neon Tetras

Neon tetras or neon tetras refer to the mini-sized tetras which are actually the smallest Characiformes that grow no more than 5cm. Many smaller tetras are considerably more peaceful and not picky on foods compared to the exotic Characiformes.

These are some Characiformes species you can consider for your aquarium

  • Neon Tetra
  • Bleeding Heart Tetra
  • Serpae or Blood Tetra
  • Buenos Aires Tetra
  • Glowlight Tetra
  • Flame Tetra
  • Black Widow Tetra


They’re standard Characiformes fish that every aquarist can start with but you better research each species further before deciding ones to live in your tank.

Characiformes Tank Requirements & SetUp / Tank Guides

This species, especially the tetras, need a specific tank setup to produce an aquarium environment that can accommodate or recreate its natural environment. Therefore, you need to properly take care of the water parameters, use an ideal tank, and apply water features.

They are absolute freshwater fish that can’t tolerate saltwater or brackish water. Be mindful when using salty materials for maintenance or other purposes.

These fish live in an acid water environment so you need to control the water pH range of 6.0 – 7.5. Be sure to also count other tank elements that may affect the current water acidity. Keep the water free from ammonia or under 5 ppm to prevent health issues.

You need to keep the water hardness no more than 8.0 dGH or your Characiformes fish may experience some health issues. Your tetras may have dull colors when the water goes above the proper hardness.

All fish are tropical species that need warmer water of 28 C to 30 C.  Keep the Nitrites and Nitrates at the lowest ppm or 0 levels for the best aquarium environment for Characiformes.

It’s very important to change the aquarium water regularly depending on the feeding frequency per day and per week,  the produced waste, the amount of Characiformes in a tank, and other possible factors.

They generally need more swimming space and proper schooling. The tank must have open swimming sections and areas with robust aquatic plants.

The aquarium for Characiformes must be 20 gallons or bigger with a horizontal aquarium that is more ideal to cater to the shallow to moderate water depth. This way, fish can be schooling with no problems in the tank.

You better setup heavily planted spaces in the aquarium with plant-grade substrate and proper lighting to promote a comfortable breeding environment for tetras.

Not only does it require warmer water, but Characiformes live in mild currents so you need to set the modest current flow. You may require low-output pumps on your tank setup instead of the robust ones. A thermometer and thermostat would be an inevitable investment for the tank setup.

You can boost the aquarium environment with additional elements to help Characiformes fish easily thriving. These include floating plants, leaf litter, tannins, and other materials.

Characiformes Tank Mates

It can survive and get along well in the community aquarium with non-aggressive inhabitants that share the same carnivore diet. You can’t, of course, put omnivore fish in the same tank except they’re meant to be the living foods.

The basic rule for aquarium is to put at least six tetras for a school but a larger population would be more ideal for them. You can put up to 30 Characiformes fish in the same 20-gallon aquarium.

You can have different Characiformes species in the aquarium but be sure to have six fish for each species so they can properly school around the tank. They prefer living in large schools and that’s also how they would breed, spawn, and birth. Other fish could be food for them.

If you’re a beginner aquarist, you better avoid this Characiformes species: Piranha. It requires specific handling and would simply eat all other fish in the aquarium. Piranha is one of those exotic species you better avoid when considering Characiformes for your aquarium.

Characiformes Diets/Food/Feeding

Some fish aren’t picky on foods in general as they’d accept flakes, frozen foods, and live foods with no problem.  Some species can even accept ordinary aquarium foods. However, since they’re basically carnivore fish, meaty foods are the main source of their nutrients.

If you’re using processed foods for carnivore fish, be sure to use the quality products and learn the nutritional factors before including them in the regular diet of your Characiformes.  For practical reasons, processed foods can be part of the regular diet that you can boost with live foods.  

Characiformes Breeding guideline

This fish would only be breeding, spawning, and giving birth in large numbers. Males would attract females by displaying to rival males on the particular spots in the tank they’ve chosen.

The robust and densely planted areas would become the perfect place for Characiformes’ courtship and breeding.

Males and females in courtship would flash their fins and come closer to each other. Whenever successful, female Characiformes would release the eggs and the males would fertilize them.

The substrate, plantation, vegetation, or egg traps you’ve previously set would be where the eggs will fall into. Characiformes, especially tetras, can lay up to 300 eggs in breeding where the hatching rate is way lower than the number.

The number of surviving fry from eggs would depend on two main factors. First, some eggs could be too sensitive to the water conditions(too acidic or less acidic). Second, the parents may eat the eggs as a natural habit of adult Characiformes. While the second scenario looks rude, it’s effective population control.

With hundreds of eggs to hatch into fry, you’d soon have an overpopulation problem for your 20-gallon tank. Except you’re a professional breeder, you don’t necessarily need a separate breeding tank for your Characiformes fish.

Characiformes Interesting Facts

Characiformes have literally thousands of different species spread into several families. While they’re different in size and colors, they share the same characteristics including the ray-finned on the back, jaws toothed, and can generally live well in community aquariums except for the Piranha.

Tetras are the most popular Characiformes fish for aquarium trades. Some of these tetras have calmer personalities and are not picky about foods. That’s why tetras are standard choices that every curious Characiformes aquarist can start with.