Red Tail Shark ~ Epalzeorhynchos bicolor

The Red Tail Shark is a striking freshwater fish known for its jet-black body contrasted by a vivid, flame-red tail. Native to the river basins and flooded forests of Thailand, this species stands out as an energetic, confident swimmer with a commanding presence in the aquarium. Although often mistaken for a peaceful community fish due to its size, it is better classified as semi-aggressive, highly territorial, and best suited for aquarists who can accommodate its need for space and structured tank mate selection.

• Size: 4-6 inches

• Lifespan: 5-8 years

• Temperament: Semi-aggressive, territorial

• Group/Solitary: Kept singly; multiple specimens require very large tanks with careful territory partitioning

• Food: Omnivorous, sinking pellets, spirulina, live/frozen foods, algae-based supplements

• Water Requirements: 72-79°F, pH 6.5-7.5, moderate hardness

Red Tail Sharks thrive in aquariums with abundant hiding spaces, such as caves, driftwood, and dense plants, which help reduce territorial tension. A minimum tank size of 55 gallons is recommended to give them enough horizontal swimming room and the ability to claim a territory without harassing tank mates. Appropriate companions include fast-moving midwater species that can avoid confrontation, while bottom-dwellers and other similarly shaped fish should generally be avoided. Their diet should include high-quality sinking pellets or wafers supplemented with spirulina and protein-rich foods like bloodworms or brine shrimp. Stable, well-oxygenated water with low organic buildup is essential for keeping this species healthy.

In nature, Red Tail Sharks once inhabited slow-moving rivers, floodplains, and densely vegetated wetlands in Thailand, where they foraged along the substrate and defended territories among branches and roots. Their wild population has suffered dramatically due to habitat loss, and most fish in the aquarium trade today are captive-bred. Their preference for shaded areas and structured environments reflects the heavily vegetated conditions of their native waters.

Fun Fact: Despite being called a “shark,” the Red Tail Shark is actually a type of cyprinid, related to barbs and rasboras, and its sharp, streamlined look comes from convergent evolution rather than any relation to true sharks.