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Rainbow Shark
Epalzeorhynchos frenatum
Animalia›Chordata›Actinopterygii
📍 Southeast Asia
A sleek, torpedo-shaped cyprinid from Southeast Asia with a dark grey body and vivid red-orange fins on all fins, reaching about 6 inches. Despite the name it is not a true shark; it is territorial and semi-aggressive toward its own kind and similar-looking fish, and should typically be kept as a single individual in a tank of 55+ gallons with plenty of hiding spots.
Care Guide
Diet
Rainbow Sharks are omnivorous bottom feeders that require a varied diet of high-quality sinking pellets, algae wafers, and occasional frozen foods like bloodworms and brine shrimp. Feed once daily, providing only what they can consume in 2-3 minutes. Supplement with blanched vegetables like zucchini or spinach 2-3 times weekly to support digestive health.
Behavior
Rainbow Sharks are highly territorial and aggressive toward their own species and similarly-colored fish, making them best kept as solitary specimens. They are primarily nocturnal bottom-dwellers that spend most of their time foraging along the substrate and hiding in caves or dense vegetation. They may harass peaceful community fish, particularly other bottom-feeders, so careful tank mate selection is essential.
Breeding
Breeding Rainbow Sharks in captivity is extremely difficult and rarely successful in home aquariums. They require very specific water conditions and large spawning territories that are difficult to replicate. Most specimens in the hobby are wild-caught or commercially bred in specialized facilities, making captive breeding impractical for hobbyists.
Tank Mates
Both are bottom-feeders; monitor closely for territorial aggression from the shark
Larger and more robust than Otocinclus; can hold their own against mild aggression
Mid-water swimmers that avoid competition with bottom-dwelling shark
Fast-moving schooling fish that stay in upper water column away from shark
May be harassed; provide plenty of hiding spots and monitor behavior
Hardy plant that provides essential hiding spots and doesn't require uprooting
Common Diseases
Ich (White Spot Disease)
White spots covering body and fins, rapid breathing, lethargy, rubbing against objects
Raise temperature gradually to 28-29°C, perform daily 25% water changes, use aquarium salt or ich medication; treat for 7-10 days
Fin Rot
Frayed or deteriorating fins, discoloration at fin edges, fin loss
Improve water quality with frequent water changes, remove sharp decorations, use antibacterial medication if severe; ensure good filtration
Bacterial Infections
Open sores, ulcers on body, cloudy eyes, loss of appetite, color fading
Perform 50% water change immediately, use broad-spectrum antibiotic medication, maintain pristine water conditions and reduce stress
Parasitic Infections
Excessive scratching, visible parasites, weight loss, clamped fins, lethargy
Use anti-parasitic medication, increase aeration, perform frequent water changes, quarantine if possible to prevent spread
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Varieties
Tips from the community 💡
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Water it likes
- ph
- 6.0–7.5
- ammonia
- 0 ppm
- nitrate
- <20 ppm
- temperature
- 72–79°F (22–26°C)