Red tail shark care guide

Red tail shark (Epalzeorhynchos bicolor) is a freshwater aquarium fish from Cyprinidae family. The red tail shark is definitely not for community tanks due to its aggressive behavior towards its tank mates. It’s quite unusual and not demanding fish that attracts attention with its rare body coloring – contrasting combination of almost black and red colors.

Habitat in the wild

The red-tailed shark is endemic to shallow algous ponds of Thailand with clean flowing water (for example Chao Phraya – the Mekong River tributary). Some specific habitats for this species are unknown; however, other species inhabit in rivers and streams or migrate to forests and bottom-lands during raining season.

This migration connected with the fish spawning period is assumed to be disturbed nowadays as a result of human intervention. Therefore, the red tailed shark population in the wild has decreased drastically and because of this species is listed in Red Book of International Union for the Conservation of Nature and Natural Resources.

Though, they say that the reason for this is, first of all, excessive capture of the fish for the aquarium trade, nevertheless the negative impact of the environmental changes is considered to be more probable cause, for example, it may be the damage done by dam construction and bog reclamation.

Scientific NameEpalzeorhynchos bicolor
Common NamesRed-tailed black shark; red tail shark; red tailed shark
Range and habitatThailand
Size16 cm (6 in)
Lifespan5 years
Ease of keepingEasy
Minimum tank size200 liters (52,83 gallons)
Temperature21–27 °C (70–81 °F)
Water hardness5-15 dGH


Red tail shark body may be up to 16 cm (6 in) long and its life span is about 5 years. Body is slim, elongated and flattened from sides with curved back.

On the red-tailed shark small head there is a pair of large red eyes, its inferior mouth has two pairs of barbs and setules, it is cupule- shaped and the fish uses it to scraper different organisms and algae from the tank bottom. The main coloring is velvet black, its fins are large and also black – the dorsal is high and sharpened, while anal, abdominal and pectoral fins are transparent and well-developed. The fluke is bright red, long and bifurcated.

Difficulties in keeping

There’s nothing difficult as for red tailed shark care, but the fish is quite large and it has aggressive temper. Therefore, it can’t be recommended to the beginners and it shouldn’t be kept in small tanks.

Care and keeping in a tank

Tank size

To keep red tail shark you’ll need a tank capacity starting from 200 liters (52,83 gallons).

Tank decor

Despite the fact that the fish requires sufficient number of places to hide, it is not demanding as for the tank decorations and it doesn’t harm any tank plants with soft leaves. However, it’s recommended to recreate natural habitat in a tank, i.e. a fast flowing river with bottom substrate of different size.

You may use gravel, stones and pebbles as a tank substrate and also put some tree roots and braches into the tank as well as water plants of Microsorum, Bolbitis or Anubias kind, which can stick to tank decorations.

Bright light will ensure active growth of algae, which is necessary for diet. Just like other species that inhabit in fast rivers the fish can’t stand accumulation of organic precipitate in the tank, since the fish prefers clean water with high oxygen content and moderate stirring.

Water parameters

Optimal water parameters for red-tailed shark keeping are the following: temperature 21–27 °C (70–81 °F); pH 6.0-8.0 (neutral value is optimal), and water hardness between 5 and 15 dH.


Red tail shark feeds mainly on algae, less on small crustaceans and maggots. You may often see how this fish scrapes algae from stones in the tank, but the fish prefers diversified feed with vegetable additives.

You may feed the fish with some daphnia, blood worm, brine shrimp in combination with high quality dry feed and some vegetable food (cucumber, green peas, peeled squash, spinach, sliced fruits).

Tank mates

Though red-tailed shark is sold as a fish for community tanks, in fact, it isn’t so. However, it doesn’t mean that the fish should be kept separately; it just means that you should more carefully choose tank mates.

Juveniles are very timid and they tend to hide in some dark tank corners, while the adult species are rather territory dependent and behave aggressively towards their tank mates that look like them. Some species are more aggressive, than others.

You should exclude bottom dwelling fish (such as cichlids and the majority of catfish species) from the list of tank mates, since they may be attacked by the fish. To occupy upper water layer in the tank you should choose small active schooling fishes.

Ideally, it’s better to put red tail shark the last into the tank. Probably, in the wild this fish prefers solitary way of life and they get together only for spawning season. In captivity this instinct is preserved and it gets stronger, therefore it’s better to keep the adult alone.

In a very large tank with large number of hide-places it’s possible to keep several red tail shark species, however each fish will require at least 1 meter of the tank length.

Then who can get on well with red-tailed shark? These are characin and carp species, small and fast fishes. All these fishes are too fast for red tail shark to catch them and they inhabit in upper and middle water layers. For example: glowlight tetra, emperor tetra, rummy nose tetra, cardinal tetra, neon tetra.

Gender differences: male vs female

You almost can’t see between red tail shark male and female. Reproductive female has more fat and rounded abdomen, but this is all that differs her from the male. As for the juveniles you won’t be able to see between the male and female.


As far as it is known this species doesn’t breed in captivity in private tanks, however the fish is bred on the farms where they use hormones for this. It is supposed to be possible to keep the number of red tail shark population in the wild only due to the farms.

Despite the fish high popularity among aquarists, it’s quite seldom kept in ideal conditions. Juveniles are usually sold without providing its owners with full information about the behavior and temper, its size when it becomes an adult fish and that its life span equals to about 8 years.

Quite often red-tailed sharks are sold as algae eaters. But keep in mind that, though the fish eats algae, it does this in smaller amounts than Crossocheilus species, therefore red-tailed shark won’t do as a tank cleaner.