Red Tailed Black Shark (Epalzeorhynchos bicolor)

Written by Kmuda. Posted in About Fish


Jet Black Body and Bright Red Tail - Sign of a healthy fish and tank

Aka: Red Tailed Shark, Labeo bicolor

Max Size: 6 inches

Minimum recommended tank size: 30 gallons

pH range: 6.0 – 7.5

Water Hardness (dH): 5-18 (from soft to medium). Does not do well in hard water.

Temperature: 73-84 (F) .

Aggression: Surprisingly Aggressive. Can be a major bully

Sexing the Red Tailed Black Shark: Virtually Impossible

Red Tailed Black Shark Lifespan:

Most literature I find list the lifespan of these fish at about 6 years, which is the longest I’ve been able to maintain one. However, there are reports of this fish living for 19 years, something I am shooting for with my current RTBS.

Red Tailed Black Shark Diet:

Omnivore – The primary component of a Red Tailed Black Sharks diet should be algae growing naturally in the tank. However, it is good practice to supplement their diet with a quality, algae based, flake food. Since they have downward turned mouths, their consimption of flake foods occurs in a unique (almost humorous) fashion (the eyes and mouth are not aligned for such coordination.) They absolutely adore bloodworms (both frozen and freeze dried) and will go nuts over freeze dried Tubifex worms (pressed to the glass). Including these meaty foods as a weekly supplement to their diet is a good practice.

A good crop of algae is absolutely recommended for a Red Tailed Black Shark tank so if you find algae unsightly, this is not the fish for you. They spend almost the entirety of their day grazing algae from filter tubes, sponges, the lips of HOB filters (fighting the overflow), plant leaves, and tank ornaments, although, unlike plecos, they will rarely graze on the walls of the aquarium aside from looking for food stuck at the water line.

If feeding flakes, I do recommend a quality spirulina based flake. Read the labels. If the first ingredient is "fish meal" and Algae and Plant meal are listed on down in the list (usually about 4 or 5 ingredients down), it's not a true veggie food. What you need is a true "veggie" food. The two I use are Ocean Nutrition Spirulina Flakes and Omega One Veggie Rounds.


This fish is actually a carp, not a shark. But, with the high dorsal fin and torpedo shaped body, they do classically resemble a shark. From 1996 to 2011, they were thought to be extinct in the wild. In 2011 a population was discovered at a single location in Thailand (the Chao Phraya basin). Even with this discovered population, it remains on the critically endangered list and it may be, in the near future, the only place these fish will be found is in our aquariums.

Breeding the Red Tailed Black Shark

There are no known reports of this fish breeding in a tank. Red Tailed Black Sharks that are available in the hobby are farm bred (ponds), induced by the artificial introduction of hormones.

Red Tailed Black Shark Tank Mates

From my youngest days (back when aquariums had stainless steel frames and slate bottoms), the RTBS has been one of my favorite fish. Their shark like appearance will certainly appeal to the macho side of anyone, especially young male children. However, make no mistake, these fish do not coexist well with all other fish. They certainly should be the only RTBS in the tank as they are very aggressive with their own (or similar) kind. I also discovered they do not coexist well with most cichlids. As an example, it has been my experience that firemouths and RTBS will constantly harass each other.

Although I am aware of reports to the opposite, I have had very good luck with Red Tailed Black sharks being housed with Angefish, although there will certainly be some skirmishes. Perhaps the best tank mate (of substantial size) has been my Kissing Gourami. I’ve also experienced few problems with RTBS housed in a general community tank. They will moderately harass their tank mates but as long as the tank mates do not strike back, the harassment will remain a low risk.
Other fish that I’ve had luck housing with RTBS are Dwarf Gouramis, Serpae Tetras, Rosey Barbs, Buenos Aires Tetras, Cherry Barbs, Danios, Cories, Neons, and Cardinal Tetras.

I do not recommend keeping these fish with Oscars or other large (or even medium) cichlids. Their tendency is to be a bully and some fish cannot be bullied, especially when even a full grown RTBS can easily fit in the mouth of some of these fish. Not only that, but a RTBS’s dental work cannot compete with a cichlid and the concept of surrender does not appear to be within their mental make up. I find that they are usually the instigator of fights with cichlids and even when not, will not give it up. If you want a fish with a macho, "you talking to me" attitude, this one certainly fits that bill (at least with other fish.) My prior RTBS had a never ending skirmish with a firemouth. I ended up moving the firemouth, not because he was loosing as he was the victor in each confrontation. But the RTBS just kept going back for more.

Keeping Red Tailed Black Sharks

Over the years I have kept many RTBS, discovering their survival rate is non-existent when kept in very hard water but they thrive in soft water. Nor do they withstand temperature changes. I lost my previous 6” RTBS following a water change mistake where the water was too cold (temperature swing of about 8 degrees). All other fish in the tank survived (including my Kissing Gourami), the RTBS did not. He developed dropsy like symptoms and expired within a few days.

One of the reasons I am a fan of RTBS is because they can be considered the canaries of the aquarium world. The very features that give them their name, the red tail and black body, are very good indicators of overall tank health. A RTBS with a jet black body and bright red tail is sure indicator of a healthy tank. If the body fades to grey and the tail goes white, this is an indication of a problem. This said, don’t be alarmed when you turn the lights on in the morning and you notice your RTBS's color is pale. This is normal. Provided all other aspects are up to par, the body will go black and the tail will return to red in short order.

Overall, I find the Red Tailed Black Shark to be an exceptional fish when kept in the proper circumstance. They are amongst the most attractive freshwater fish and can serve as a feature fish in a community setting.