Care Requirements
Adult Size
5.9" (15cm)
Min Tank
55 gal
Temperature
72-79°F
pH Range
6.5-7.5
Lifespan
5-8 years
Min Group
Can be kept alone
Diet
Omnivore
Swim Level
Bottom
Bioload
4/10
Hardness
5-15 dGH
About Red Tail Shark
The Red Tail Shark (Epalzeorhynchos bicolor) is one of the most recognizable freshwater fish with its jet-black body and vivid red tail. Despite the name, it's not a shark at all — it's a cyprinid, more closely related to barbs and minnows. Native to Thailand's Chao Phraya basin, they're critically endangered or possibly extinct in the wild due to habitat destruction. All aquarium specimens are captive-bred. While stunningly beautiful, they're highly territorial and aggressive toward other bottom-dwellers, making tankmate selection critical. They're long-lived at 8-10 years and grow to 6 inches.
Natural Habitat & Origin
Conservation status: Critically Endangered (CR)
Red Tail Sharks are native to clear, flowing streams and rivers in Thailand's Chao Phraya basin with rocky substrates and algae-covered surfaces. They inhabit well-oxygenated water with moderate current. Tragically, they're critically endangered or possibly extinct in the wild due to habitat destruction. All aquarium specimens are captive-bred.
Native Region
Thailand — Chao Phraya basin (critically endangered/possibly extinct in wild)
Habitat Type
Clear, flowing streams and rivers with rocky substrates and algae-covered surfaces
Wild Water Conditions
Well-oxygenated water with moderate current
Appearance & Varieties
Red Tail Sharks have a sleek, torpedo-shaped body that's completely jet black, contrasted by a vivid red or deep orange tail fin. They grow to about 6 inches (15cm). The prominent dorsal fin gives them the 'shark-like' silhouette that earned their common name, though they're not related to true sharks. Sexing is very difficult — females may be slightly rounder when full of eggs, and males may have a slightly more pointed dorsal fin, but differences are subtle.
Tank Setup & Requirements
Quick Requirements Summary
Tank Size
Minimum Tank Size
55 gallons
Recommended Tank Size
75 gallons
Red Tail Sharks need a large tank (55+ gallons minimum, 75+ recommended) with significant floor space for territory. A long tank is better than a tall one. Sand or fine gravel substrate allows natural grazing behavior. Well-planted tanks with caves, driftwood, and rock formations are essential to create multiple territories and visual barriers that reduce aggression toward tankmates. Moderate to strong flow mimics their stream habitat. ONE per tank only — they will fight with conspecifics and similar species.
Water Parameters
Temperature 72-78°F (22-26°C), pH 6.5-7.5, hardness 5-15 dGH.
Substrate
Sand or fine gravel — allows natural grazing behavior
Plants & Decorations
Well-planted tanks with caves, driftwood, and rock formations essential. Create multiple hiding spots and visual barriers to reduce aggression to tankmates.
Filtration & Water Flow
Moderate to strong flow — they come from flowing streams
Lighting
Moderate — promotes algae growth they can graze on
Diet & Feeding Guide
Diet Type
Omnivore
Feeding Frequency
1-2 times daily
Portion Size
What they can consume in 2-3 minutes
Red Tail Sharks are omnivores that primarily graze on algae, plant matter, and organic detritus in the wild, supplemented by insects and small crustaceans. In captivity, provide sinking pellets, algae wafers, and spirulina-based foods as staples. Supplement with frozen bloodworms, blanched vegetables, and occasional live foods. They're not dedicated algae eaters despite being sold as such, but they do help with algae control.
Best Foods for Red Tail Shark
- Sinking pellets and algae wafers — Staple diet for bottom-feeding
- Spirulina-based foods — Important plant matter component
- Blanched zucchini and cucumber — Good vegetable supplementation
- Frozen bloodworms — Protein supplementation
- Blanched peas — Good for digestion
Foods to Avoid
- Protein-only diet — Need vegetable matter for balanced nutrition
- Floating-only foods — They feed primarily from substrate and lower water column
Primarily grazes on algae and biofilm. Supplement with sinking foods and include vegetable matter. They're not dedicated algae eaters but do help with algae control.
Behavior & Temperament
Red Tail Sharks are territorial and aggressive toward similar species and bottom-dwellers. They relentlessly chase any fish that enters their perceived territory, especially other bottom-dwellers and similar-looking fish. Critically, aggression increases with age — juveniles often seem peaceful, leading people to buy them for community tanks without realizing adult behavior will be very different. They're not true sharks but cyprinids (carp family). Despite their aggression, they generally ignore dissimilar fish in the upper water column. They're critically endangered or possibly extinct in the wild — all aquarium specimens are captive-bred.
Tank Mates: Compatibility Guide
Compatible Tank Mates
Large tetras
Active mid-water fish that stay away from bottom
Fast mid-water swimmers
Active and robust enough
Different zone, usually ignored
Fast upper-water swimmers
Tank Mates to Avoid
Other Red Tail Sharks
Will fight constantly — ONE per tank only
Rainbow Sharks
Similar species clash badly
Corydoras
Bottom-dwellers will be chased relentlessly
Plecos
Often harassed as bottom-dwelling competition
Loaches
Bottom-dwellers will be targeted
Common Pairing Questions
Can I keep more than one Red Tail Shark?
No — they're highly territorial and will fight constantly. ONE per tank is the absolute rule.
Can Red Tail Sharks live with Rainbow Sharks?
No — similar species clash badly. Never keep them together.
Breeding Red Tail Sharks in home aquariums is virtually impossible. Their extreme territorial nature makes keeping breeding groups unfeasible, and they would need very large tanks with multiple specimens that don't coexist well. All aquarium specimens come from commercial breeding operations in Asia that use hormonal inducement. Don't attempt breeding at home — focus on providing the best possible care for your single specimen instead.
Health Issues & Disease Prevention
Red Tail Sharks are moderately hardy fish. Healthy specimens display jet-black bodies, bright red tails, active grazing/patrolling behavior, and normal territorial behavior. Stress signs include faded black coloration, pale or orange (rather than red) tail, constant hiding, and loss of appetite. They're susceptible to Ich, skin flukes, and bacterial infections, particularly if injured from fighting. Good water quality and a stress-free environment are key to their health.
Common Diseases
| Disease | Symptoms | Treatment |
|---|---|---|
| Ich (White Spot Disease) | White spots, flashing, clamped fins | Raise temperature gradually, salt treatment, or medication |
| Skin flukes | Flashing, scratching, cloudy skin | Anti-parasitic medication |
| Bacterial infections | Red patches, ulcers, fin rot | Antibacterial medication, improve water quality |
Signs of a Healthy Red Tail Shark
- Jet black body
- Bright red tail
- Active grazing/patrolling
- Good appetite
- Territorial behavior (normal)
- Clear eyes
Prevention Tips
- Good water quality
- Avoid injury from fighting with suitable tankmates
- Quarantine new fish
- Stable water parameters
- Adequate tank size for territory
Frequently Asked Questions
No — they're highly territorial and will fight constantly. Even in very large tanks, keeping multiples usually results in the dominant fish relentlessly attacking others. ONE per tank is the rule.
No — they're cyprinids (carp family), more closely related to barbs and minnows. The 'shark' name comes from their body shape and prominent dorsal fin. They're freshwater fish, not marine.
This is normal — they're extremely territorial. They chase any fish that enters their perceived territory, especially bottom-dwellers and similar-looking fish. A larger tank with visual barriers helps but won't eliminate the behavior.
Yes — juveniles often seem peaceful, leading people to buy them for community tanks. As they mature and establish territory, aggression increases significantly. Plan for adult behavior, not juvenile behavior.
Red Tail Sharks have completely black bodies with red tails only. Rainbow Sharks have red/orange fins throughout (tail, dorsal, anal, pelvic fins). Both are territorial and shouldn't be kept together.
Yes — they're critically endangered or possibly extinct in the wild due to habitat destruction in Thailand. All aquarium specimens are captive-bred. Buying them doesn't harm wild populations.
Tips for Keeping Red Tail Shark
Pro Tips
- ✓ONE per tank — this is the golden rule
- ✓Plan for adult aggression, not juvenile behavior
- ✓Large tank with visual barriers reduces (but doesn't eliminate) chasing
- ✓Best tankmates are active mid-water fish that won't compete for bottom territory
- ✓They're not good algae eaters despite being sold as such
- ✓Long-lived (8-10 years) — commitment required
- ✓All specimens are captive-bred — you're not harming wild populations
- ✓Despite aggression, they're personable fish that recognize their owners
Common Mistakes to Avoid
- ✗Keeping more than one — guaranteed constant fighting
- ✗Buying as juveniles expecting peaceful behavior — aggression increases with age
- ✗Tank too small — minimum 55 gallons for territory
- ✗Keeping with other bottom-dwellers — will be chased relentlessly
- ✗Expecting dedicated algae control — they help but aren't specialists
- ✗Housing with Rainbow Sharks — similar species clash badly
- ✗No hiding spots or visual barriers — increases aggression to tankmates
- ✗Thinking 'mine will be different' — territorial behavior is hardwired
Sources
- FishBase — Accepted scientific name, maximum size and native range for Red Tail Shark.
- IUCN Red List — Critically Endangered conservation assessment for Epalzeorhynchos bicolor.
Related Species You Might Like
View All Fish →
Red Zebra
Maylandia estherae
Rainbow Shark
Epalzeorhynchos frenatum
African Butterfly Fish
Pantodon buchholzi
Amazon Puffer
Colomesus asellus
Angelfish
Pterophyllum scalare
Blood Parrot Cichlid
Amphilophus hybrid
Calvus
Altolamprologus calvus
Compressiceps
Altolamprologus compressiceps
Ready to Add Red Tail Shark to Your Tank?
Use our free stocking calculator to check compatibility, bioload, and get personalized recommendations.