Red Tail Black Shark (Epalzeorhynchos bicolor)

The Red Tail Black Shark, Epalzeorhynchos bicolor, is one of the most recognisable freshwater shark-style fish in the aquarium hobby. It has a deep dark body, a bright red tail and a confident patrolling style that makes it stand out in a planted or rocky community aquarium. Petra supplies this fish under the older name Labeo bicolor; both names refer to the Red Tail Black Shark, with Epalzeorhynchos bicolor used here as the current accepted aquarium and taxonomic name.

This is not a soft beginner community fish. It is hardy once settled, but it is territorial, active and best kept by aquarists who can give it space, cover and robust tank mates. Choose it for a mature aquarium where a single bold bottom-to-midwater fish can patrol a defined area without being crowded.

What Makes This Fish Special?

The appeal is simple: a jet-dark body against a vivid red tail. In good condition the contrast is dramatic, and the fish moves with a shark-like glide despite being a cyprinid, closer to minnows and carps than to true sharks. It often becomes a recognisable individual in the tank, claiming a route around wood, rocks and open areas.

That personality is exactly why the Red Tail Black Shark needs planning. A tiny juvenile may look harmless, but adults can become possessive over caves, food areas and lower-tank territories. A well-designed aquarium lets the fish behave naturally without turning the whole tank into one contested space.

Correct Identity

This listing is for Red Tail Black Shark, Epalzeorhynchos bicolor. Petra's source data uses Labeo bicolor, the older name still seen in the trade. It should not be confused with the Rainbow Shark or red-finned shark, which has red on more fins rather than the classic dark body and red caudal fin combination.

FishBase lists Epalzeorhynchos bicolor from the Chao Phraya basin in Thailand, with a maximum length around 13 cm and a territorial adult temperament. Modern aquarium stock is generally captive-bred, which is important because wild populations are under serious conservation pressure.

Aquarium Size and Layout

Plan for a long, spacious aquarium rather than a small cube. Young fish can be grown on in moderate tanks, but adults are much easier to manage in a larger footprint with room to patrol. For long-term care, think in terms of a mature aquarium around 150 litres or larger for a single specimen, with more space always welcome if the community is busy.

The layout should include driftwood, smooth rocks, caves, robust plants and open lanes for swimming. Break up direct sight lines so the fish can hold a territory without seeing every tank mate all the time. A bare aquarium makes the fish more exposed and can increase chasing; a structured aquarium gives it jobs, boundaries and retreat points.

A close-fitting lid is sensible. Red Tail Black Sharks are active fish and can jump if startled. Keep intakes guarded, leave space around decorations and avoid sharp rockwork that could damage the body or fins during territorial dashes.

Water Conditions

Use a mature, fully cycled aquarium with zero ammonia, zero nitrite and consistently low nitrate. Petra's range for this stock is 23-27 C, pH 6.0-7.8 and 5-20 dGH, which gives most UK aquarists a practical target as long as conditions are stable. FishBase gives a slightly narrower reference range of pH 6.5-7.5 and 22-26 C, so avoid extremes and keep the fish in steady tropical freshwater.

Good filtration and oxygenation matter because this is an active fish from flowing river and floodplain habitats. It does not need a torrent, but it appreciates clean, well-moving water. Weekly partial water changes, careful feeding and regular substrate maintenance are more useful than chasing a perfect number after the fish arrives.

Feeding

Red Tail Black Sharks are omnivores that graze surfaces and take sinking foods readily. Use quality sinking pellets or wafers as the base, then add vegetable foods such as spirulina wafers, algae-based tablets and small portions of blanched courgette or spinach. Small frozen foods such as bloodworm, daphnia, brine shrimp or cyclops can be offered as variety rather than as the whole diet.

Feed where bottom and midwater fish can all get a fair chance. A hungry Red Tail Black Shark may become more forceful at feeding time, especially in a crowded tank. Several small feeding points are better than one pile of food that everyone has to fight over.

Tank Mates

The safest approach is to keep one Red Tail Black Shark per aquarium. Avoid keeping it with its own kind or with very similar shark-like bottom fish unless the aquarium is exceptionally large and carefully structured. It may chase fish that compete for the same caves, lower-level territory or food.

Good tank mates are usually robust, active fish that occupy different areas and are not easily intimidated. Medium barbs, danios, rainbowfish, sturdy peaceful cichlids and larger community fish can work in the right layout. Avoid tiny fish, long-finned slow fish, delicate species, timid bottom dwellers and ornamental shrimp. Corydoras and loaches may be harassed in smaller aquariums because they share the lower zone.

If you want a related comparison, the Albino Rainbow Shark has a similar body style but a different colour pattern and should be planned with the same respect for space and temperament. The much larger Black Shark is a separate, bigger commitment for very large aquariums.

Behaviour and Settling

Expect a new fish to explore, hide and test boundaries during the first week. Keep lights modest on arrival day and avoid rearranging the tank repeatedly once the fish has chosen shelter. A confident specimen will often establish a patrol route, inspect hardscape and graze surfaces between meals.

Some chasing is normal territorial signalling, but constant bullying means the aquarium is too small, too open, too crowded or stocked with unsuitable companions. Add visual barriers, check feeding, and be ready to move vulnerable tank mates if one individual becomes too dominant.

Health Checks

Look for a clean body line, clear eyes, intact fins, steady breathing and a strong red tail. Faded colour can happen during stress, transport or poor water conditions, so judge the fish after it has settled as well as on arrival. Avoid sudden temperature swings, poor oxygenation, dirty substrate and aggressive tank mates, as these are the common stress points for this species.

Because the fish grazes and patrols the lower aquarium, keep the substrate clean but not sterile. Remove uneaten food, maintain flow behind hardscape and make sure caves do not trap waste. Stable care usually produces a bold, long-lived display fish.

Best Buyer Fit

Choose the Red Tail Black Shark if you want a striking, active fish for a larger mature tropical aquarium and you enjoy watching territorial behaviour. It is best for aquarists who can design the tank around the fish instead of adding it as an afterthought.

Skip it if your aquarium is small, newly set up, full of delicate bottom fish or built around very slow long-finned species. In the right tank it is dramatic and rewarding; in the wrong tank it can become stressful for both fish and keeper.

Setup Checklist Before Ordering

• Confirm the aquarium is fully cycled and mature.
• Keep temperature stable in the 23-27 C range.
• Provide caves, wood, rock and plants before the fish arrives.
• Plan for a single Red Tail Black Shark unless you have a specialist large setup.
• Choose robust tank mates that do not compete heavily for the same lower territory.
• Have sinking foods, vegetable foods and small frozen foods ready.
• Check that the lid is secure.

Ordering and Arrival

This listing covers captive-bred Red Tail Black Shark size variants supplied through Petra, with availability depending on the current stock list. Eligible livestock is packed carefully and sent by UK live-animal courier. The Live Arrival Guarantee applies when the receiving and acclimation instructions are followed. Use WELCOME10 if you are placing your first order and the code is currently available at checkout.

After arrival, keep the lights low, acclimate patiently and give the fish time to claim cover before expecting full confidence. A prepared aquarium will do more for this species than any last-minute correction.