Red-Tailed Black Shark

Epalzeorhynchos bicolor

Animalia›Chordata›Actinopterygii

📍 Thailand

A striking freshwater cyprinid native to Thailand with a jet-black velvety body and a vivid red-orange tail fin. Grows to about 5 inches and is territorial, especially toward its own kind and similar bottom-dwellers. Best kept singly in a 55+ gallon tank with caves and driftwood for hiding. Despite the name, it is not a true shark but a member of the carp family.

Size5"

Min Tank55g

semi-aggressive

Zonebottom

Care Guide

Diet

Red-tailed black sharks are omnivorous and should be fed high-quality sinking pellets as a staple, supplemented 2-3 times weekly with frozen foods like bloodworms, brine shrimp, or daphnia. They will also graze on algae wafers and appreciate occasional vegetable matter such as blanched zucchini. Feed once daily in amounts they can consume in 2-3 minutes.

Behavior

This species is highly territorial and aggressive toward conspecifics and similar bottom-dwelling fish, especially as it matures. It is primarily nocturnal and spends much of the day hiding in caves or under driftwood, becoming more active during dawn and dusk. The red-tailed black shark is a bottom-feeder that constantly forages and explores its environment.

Breeding

Breeding in captivity is extremely rare and difficult; very few successful spawns have been documented in the hobby. They require specific water conditions and large breeding tanks with minimal disturbance, and fry rearing is challenging. Most specimens in the aquarium trade are wild-caught, making captive breeding impractical for most hobbyists.

Tank Mates

Bristlenose Pleco

Similar bottom-dwelling habits but less aggressive; provide separate caves to minimize conflict

good

Emerald Dwarf Rasbora

Small, mid-water swimmers that avoid competition with bottom-dwellers

good

Neon Tetra

Peaceful schooling fish that occupy upper water column and are too small to trigger predatory behavior

good

Gold Mystery Snail

May be harassed but can retreat into shell; monitor for aggression

caution

Kuhli Loach

Nocturnal bottom-dweller; may compete for space and food; requires careful observation

caution

Common Diseases

Ich (Ichthyophthirius multifiliis)

Symptoms

White spots on body and fins, rapid breathing, lethargy, rubbing against objects

Treatment

Raise temperature gradually to 28-29°C, perform daily 25% water changes, use ich medication (malachite green or formalin) as directed; maintain good water quality

Fin Rot

Symptoms

Frayed or deteriorating fin edges, discoloration at fin bases, lethargy

Treatment

Improve water quality with frequent partial water changes, reduce stress by providing hiding spots, use antibacterial medication if severe; ensure adequate filtration

Bacterial Infection

Symptoms

Open sores, ulcers on body, cloudy eyes, loss of appetite, color fading

Treatment

Perform 50% water change immediately, use broad-spectrum antibiotic medication, isolate if possible, maintain pristine water conditions and avoid overcrowding

Parasitic Infection

Symptoms

Excessive scratching, visible parasites, weight loss, clamped fins

Treatment

Use anti-parasitic medication (praziquantel or similar), perform frequent water changes, quarantine affected fish, treat the main tank if infestation is widespread