Home / Fishes / Carp, barbs, minnows, loaches / Cyprinidae / Rainbow shark
No federal permit to keepRainbow shark
Epalzeorhynchos frenatum
Fishes › Carp, barbs, minnows, loaches (Cypriniformes) › Cyprinidae (Carps and barbs)
The rainbow shark (Epalzeorhynchos frenatum) is a species of Southeast Asian freshwater fish from the family Cyprinidae.
Care at a glance
Species-specific aquarium care
- Tank: At least 30 in long and 12 in front to back for one adult (adults commonly reach about 5.9 in / 15 cm).
- Water: Freshwater.
- Temperature: 75–81°F (range recorded for this species).
- pH: 6–8.
- Hardness: 5–12 dGH.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Diet: FishBase classes it as a omnivore.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 47 × 18 in (roughly 64 US gallons); space needed is rated “large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 68–79 °F, pH 6.5–8, 2–15 dGH.
- Behaviour: temperament territorial; kept alone; not a community fish.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Provided sufficient cover is available this species is relatively unfussy in terms of décor, and should not harm softer-leaved plants.”
- Diet: “Primarily an aufwuchs grazer feeding on algae, small crustaceans, insect larvae, etc., and for it to develop its best colours and condition it should be offered regular meals of small live and frozen foods such as chironomid larvae (bloodworm), Daphnia and…”
- Tankmates: “A slightly better choice for the community tank than E.”
- Breeding: “As far as we know it's not been bred in private aquaria but large numbers are farmed for the ornamental trade with the aid of hormones.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Carps and barbs
Applies to most species in this group. Habitat: The listed barbs and freshwater sharks occupy Asian streams, rivers and floodplain waters, with bala sharks also using natural lakes. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- Tiger barbs need a base at least 80 × 30 cm (about 31 × 12 inches), with vegetation and driftwood cover.
- Adult bala shark groups need a base at least 240 × 60 cm (about 96 × 24 inches), ample open swimming space and a heavy, tight lid.
- Red-tailed black sharks need a base at least 120 × 45 cm (about 48 × 18 inches), with rocky refuges.
- Use efficient filtration, water movement and high oxygenation for riverine bala and red-tailed sharks.
Climate & lighting
| Water | 68–78.8°F |
Diet
- Quality flakes or granules containing plant material.
- Live or frozen Daphnia, Artemia and bloodworms.
- For larger bala sharks: chopped earthworms, prawns or mussels.
- For bala sharks: shelled peas, blanched courgette or spinach.
Social life
- Keep tiger barbs in at least 8–10 and bala sharks in at least five. Avoid timid or long-finned companions for tiger barbs. Red-tailed black sharks become territorial toward similar-looking fishes.
Health watch
- Ammonia toxicity.
- Nutritional deficiencies.
Understanding the animal
About this animal
About this animal
It is also known as the ruby shark, red-fin shark, red-finned shark, rainbow sharkminnow, green fringelip labeo, whitefin shark and whitetail sharkminnow. It is a popular, semi-aggressive aquarium fish.
Quoted from the Wikipedia article “Rainbow shark” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater, in rivers and streams. Uses both the bottom and open water. |
| Water it lives in | Freshwater, 75–81 °F (24–27 °C), pH 6–8, hardness 5–12 dH. |
| Climate | Tropical climate. |
What this means for care
- Keep water within its wild range, 75–81 °F.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | The rainbow shark (Epalzeorhynchos frenatum) is a species of Southeast Asian freshwater fish from the family Cyprinidae. It is also known as the ruby shark, red-fin shark, red-finned shark, rainbow sharkminnow, green fringelip labeo, whitefin shark and whitetail sharkminnow. It is a popular, semi-aggressive aquarium fish. Unlike true sharks, which belong to the Chondrichthyes ("cartilagenous fishes") lineage, the rainbow shark is an actinopterygiian ("ray-finned fish"). — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Wild diet | Rainbow sharks are omnivores that in captivity primarily consume algae in the form of flakes, but also live foods such as insect larvae, tubifex worms, periphyton, crustaceans, phytoplankton, zooplankton and aquatic insects, and lettuce and spinach. They will also eat frozen bloodworms and brine shrimp. — Wikipedia (community-edited) |
| Behavior | Rainbow sharks are tank-bottom and aquarium-surface cleaners. Being bottom- and mid-level dwellers, they consume leftover fish food, but also eat the algae growing off surfaces. They are generally peaceful with their own kind in the wild, but they can become aggressive with each other if kept in a tank. — Wikipedia (community-edited) |
| Reproduction | No actual breed sequence has been documented in an aquarium setting. Although known to be egg-layers, reproduction of rainbow sharks is difficult in an aquarium setting. Large numbers are bred in southeast Asian commercial farms. — Wikipedia (community-edited) |
| Appearance and size | The rainbow shark has an elongated black, dark blue or bright blue body. The abdominal area is flat. The fins possess red to orange-red coloration. — Wikipedia (community-edited) |
| Biology | Observed over sandy substrate. Found near any type of solid surface at midwater and bottom depths in streams and rivers. Moves into seasonally flooded habitats and returns to the rivers as floodwaters recede. — FishBase |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Adult length
Maximum recorded length. Measured as total length. Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
Minimum tank footprint
Seriously Fish recommends a tank base of at least 47 × 18 in (about 64 US gallons).
Veterinary & husbandry research
Veterinary & husbandry research
- Risk of Spread of Megalocytivirus pagrus1 (Infectious Spleen and Kidney Necrosis Virus) From Frozen Fillets Becker JA et al., Journal of fish diseases 2026
Peer-reviewed papers that mention this species alongside captivity, zoos, veterinary care or aquaculture. Some cover several species or mention it only in passing, so check the abstract. 170
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Seriously Fish — Puntigrus tetrazona Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish — Balantiocheilos melanopterus Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish — Epalzeorhynchos bicolor Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual — Disorders and Diseases of Fish Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- PubMed (U.S. National Library of Medicine) Peer-reviewed researchIndex of peer-reviewed veterinary, zoo and husbandry research.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.
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