The Red-tailed Black Shark is a striking fish with a velvety black body and vivid red tail, widely prized by aquarists for its bold appearance.
Overview
The Red-tailed Black Shark (Epalzeorhynchos bicolor) is one of the most recognizable freshwater aquarium fish, belonging to the family Cyprinidae. In the wild, this species originally inhabited the Chao Phraya river basin in Thailand, but by the late 20th century it was nearly extinct in its natural habitat due to environmental destruction. Today, the vast majority of specimens available in pet stores are bred on fish farms in Southeast Asia.
The appearance of Epalzeorhynchos bicolor is unmistakable: a velvety black, torpedo-shaped body contrasted by a brilliant red caudal fin. Adults reach 12-15 cm in length. The mouth is ventral, equipped with two pairs of barbels, typical of bottom-dwelling members of the carp family. With proper care, they can live 5-8 years in an aquarium.
Despite the common name "shark," Epalzeorhynchos bicolor has no relation to true sharks. The nickname comes from the distinctive shape of the dorsal fin and the fish's energetic swimming style. This is an active, territorial fish with a strong personality that can become a true centerpiece of an aquarium when kept properly.
Tank Requirements
Keeping Epalzeorhynchos bicolor requires an aquarium of at least 100 liters. This species is territorial, so it is important to provide enough space with clear zone divisions. Driftwood, rocks, and dense plant thickets are recommended to create natural territorial boundaries and hiding spots.
Optimal water parameters: temperature 22-26 °C, pH 6.5-7.5, general hardness (GH) 5-15 dGH. The Red-tailed Black Shark prefers clean, well-oxygenated water with moderate current that mimics river and stream conditions. A dark substrate of sand or fine gravel is best, as it makes the fish's coloration appear most striking.
The aquarium must be equipped with a tight-fitting lid, as Epalzeorhynchos bicolor is capable of jumping, especially in stressful situations. Lighting should be moderate, with shaded areas available.
Feeding and Diet
Epalzeorhynchos bicolor is an omnivorous species with a predominantly herbivorous diet. In the wild, the fish feeds on algae growth, small invertebrates, and plant debris. In the aquarium, the dietary foundation should consist of high-quality sinking granules or tablets designed for bottom-dwelling fish.
As supplementary foods, regularly offer:
- blanched vegetables such as zucchini, spinach, and cucumber;
- spirulina-based foods;
- frozen bloodworms and brine shrimp;
- daphnia and cyclops.
Feed 1-2 times daily in small portions. It is worth noting that the Red-tailed Black Shark actively grazes on algae growth in the aquarium, which serves as a useful supplement to the main diet. However, do not rely on algae alone — if algae are scarce, the fish may start nibbling on the leaves of soft plants.
Care and Maintenance
To maintain the health of Epalzeorhynchos bicolor, regular water changes of 20-25% of the volume are needed weekly. Filtration should be efficient, providing both mechanical and biological cleaning. An external canister filter that creates moderate current is recommended.
Check the key water parameters weekly: ammonia and nitrites should be at zero, and nitrate levels should not exceed 20-30 mg/L. The Red-tailed Black Shark is sensitive to high concentrations of nitrogenous compounds, which can lead to faded coloration and weakened immunity.
Regularly inspect the fish for signs of disease: faded coloring, white spots (ich), or ragged fins. If symptoms appear, prompt action is important — quarantine and treatment. Keep an eye on the condition of decorations and hiding spots: Epalzeorhynchos bicolor actively uses caves and crevices, so their construction should be safe and stable.
Compatibility
Epalzeorhynchos bicolor is a territorial fish capable of marked aggression, especially toward conspecifics and species with similar coloration or body shape. Keeping two Red-tailed Black Sharks in the same aquarium is strongly discouraged, except in very spacious tanks (300 liters or more) with abundant hiding spots.
Suitable tank mates are active, fast-swimming fish of medium size:
- tiger barbs and other large barbs;
- zebra danios and other danios;
- Congo tetras and other larger tetras;
- rainbowfish;
- clown loaches.
Not recommended to keep with:
- the closely related Rainbow Shark — territorial conflicts are inevitable;
- slow, docile fish such as angelfish and gouramis;
- small species such as neon tetras and rasboras;
- other bottom-dwelling fish occupying the same zone of the aquarium, such as Siamese algae eaters and Chinese algae eaters.
Breeding
Breeding Epalzeorhynchos bicolor in a home aquarium is an extremely challenging task that only a handful of hobbyists have accomplished. The breeding difficulty is rated 4 out of 5. On commercial farms in Southeast Asia, hormone injections are used to stimulate spawning, which is virtually impossible to replicate at home.
Sexual dimorphism is minimal: females are typically slightly larger and fuller than males, with a more rounded abdomen. Males ready to spawn may display somewhat more intense coloration.
For a breeding attempt, a separate spawning tank of at least 150 liters is needed with soft, slightly acidic water (pH 6.5-7.0, temperature 25-26 °C). Flat rocks and broad-leaved plants should be placed on the bottom. Spawning usually occurs in the morning hours; the female scatters up to 40-50 eggs that fall onto the substrate. After spawning, the parents must be removed immediately, as they are inclined to eat their own eggs.
Incubation lasts 48-72 hours. The newly hatched fry should be fed infusoria, and after several days transitioned to baby brine shrimp (Artemia nauplii). Fry grow slowly and develop the characteristic adult coloration by 2-3 months of age.