Red eye tetra care guide

Red eye tetra (lat. Moenkhausia sanctaefilomenae) once was the most spread and common tetras in a tank. A school of these characins can make any tank look nice and lively, but nowadays the fish has yielded the palm to other fishes. Is a peaceful active fish, quite easy in care. This fish needs to be in the school much more unlike it’s relative redeye tetra. Regardless of how many of them are in a tank: three, eight or twenty species – they always swim in a school.

Habitat in the wild

Red eye tetra was first described in 1907. It inhabits in South America, Paraguay, Bolivia, Peru and Brazil. In the wild the fish lives in pure, flowing waters of big rivers, but sometimes it may swim to tributaries to search for feed in thick plants there. This is a schooling fish and it feeds on insects.

Scientific NameMoenkhausia sanctaefilomenae
Common NamesRed eye tetra; lamp eye tetra; red eye fish
Range and habitatSouth America
Size7 cm (2.8 in)
Lifespan3 years
Ease of keepingMedium
Minimum tank size80 liters (20 gallons)
Temperature21–27 °C (70–81 °F)
Water hardness5-20 dGH


Red eye tetra size is up to 7 cm (2.8 in) and its lifespan is about 3 years. Exists two types red eye tetras known to aquarists:

  • red eye tetra
  • balloon red eye tetra

Balloon red eye tetra it is smaller and it has more wide than long body, so it looks more rounded.

Difficulties in keeping

Care is easy since it’s not a demanding fish, so it’s good for beginner. As we’ve already mentioned – the red eye tetra is active, peaceful and if it is a balloon species, it also keeps the school well. Red eye tetra has a very social behavior and it prefers swimming in schools of 5-6 fishes.

Care and keeping in a tank

Red eye tetra prefers lower and middle water layers. It’s desirable to keep a school of 5-6 fishes or more in a tank of 15 gallons capacity minimum. Since the fish can jump, you should keep it in closed community tank (more than 40 cm long) with some shaded by the plants areas. Red eye tetra doesn’t like strong water flow, so make sure that the filter doesn’t create one.

In the wild the fish habitat doesn’t have a lot of light, because the shores of the rivers have lots of greenery. It’s better if the tank has soft lighting which can be achieved by putting some floating plants on the water.

Each week renew up to 20-25% of total water amount. Water parameters: 21–27 °C (70–81 °F), pH 6.5-7.5, 5-20 dGH.

Tank mates

The red eye tetra is good for community tanks at the condition that it’s kept in a school. However, they may scare more calm fishes, since it’s very active, so you just have to choose the same active tank mates for it.

For example, it can be black skirt tetra, emperor tetra, cardinal tetra. Also tetra may nip other fishes fins, so don’t keep them with long-finned fishes or other slow fishes with large fins, for example, with angelfishes.

If there’s no such possibility, you may smooth this kind of the fish behavior by keeping it in a school where the fishes have an hierarchy and they become busy with the species of their kind.


Fish is omnivorous and in a tank it feeds on all kinds of live, frozen or artificial feed. If you add some plant feed into the diet it’ll make the fish more healthy and brightly colored.

Gender differences: male vs female

The only real difference between red eye tetra male and the female is that the latter is more rounded and fat.


Red eye tetra become reproductive approximately at the age of 10 month. Breeding should take place in a separate tank from 2 gallons capacity, covered from top.

It should also have some Java moss or a separating grid on the bottom. The tank water should be warmer (24-28 °C), acidic (6-6,8) and soft (до 6°). Before spawning you should prepare the fishes: put them is a separate tanks, feed well and add some plant food into the diet.

The fishes that were put into spawning tank in the evening start their mating game within the tank plants in the morning. The female lays up to 1000 sticky eggs that lay on the tank bottom or get stuck on the plants leaves.

At the end of spawning period the fishes are removed from the tank and you should start light aeration in it. The fish is very fruitful. The eggs incubation time is about 1-2 days. On the 5-6th day larva become juveniles and they start feeding on small nauplii of brine shrimp.

The juveniles are very small from the beginning, therefore the brine shrimp should be small correspondingly, the same concerns cyclops nauplii, rotifers or infusorian. Juveniles grow slowly even despite well balanced and high diet.