Rainbow shark care guide
Also called: Ruby shark, Red-finned shark, Rainbow sharkminnow, Albino rainbow shark, GloFish shark, GloFish rainbow shark
The rainbow shark is a sleek bottom-dweller with bright red fins, sold in dark, albino and GloFish colors. It's territorial, so keep just one per tank, in a tank at least 4 ft by 18 in (120 × 45 cm), such as a 75-gallon (284 L), with caves and fast-moving tankmates.
Rainbow sharks need a tank of at least 75 gallons (284 L), and water at 22–26°C (72–79°F) with a pH of 6.5–7.5. They grow to about 15 cm (5.9 in) and are semi-aggressive.
Plan a tank with rainbow sharksSee all tank mates
Rainbow shark quick facts
| Scientific name | Epalzeorhynchos frenatum |
|---|---|
| Family | Cyprinidae |
| Origin | Mekong, Chao Phraya and Mae Klong basins in Thailand, Laos and Cambodia (aquarium fish are farm-bred; GloFish forms are captive-bred only) |
| Adult size | 15 cm (5.9 in) |
| Minimum tank | 75 gallons (284 L), at least 120 cm (47 in) long |
| Temperature | 22–26°C (72–79°F) |
| pH | 6.5–7.5 |
| Hardness (GH) | 5–12 dGH |
| Group size | Can live alone |
| Temperament | Semi-aggressive; fights its own kind |
| Swims at | Bottom |
| Diet | Omnivore |
| Care level | Moderate |
| Lifespan | 5–8 years |
| Safe with shrimp? | No, eats shrimp |
| Safe with plants? | Yes |
- Known jumper: keep a tight-fitting lid.
Tank setup
One rainbow shark needs a tank at least 4 ft (120 cm) long and 18 in (45 cm) front to back, such as a 75-gallon (284 L), because it patrols a large area. A standard 75 gallon fits; most 55-gallon tanks are too narrow. Add caves, rockwork, driftwood and plants to break up sight lines, and leave open bottom space for grazing. Sand or smooth gravel is best. Keep the lid tight, as they jump.
How many rainbow sharks in a tank?
The smallest common tank that suits rainbow sharks is a 75 gallon. Here is roughly how many fit in each size when they are the only fish, based on adult size and waste output. Leave room if you want tank mates.
| Tank | Rainbow sharks (alone) |
|---|---|
| 3 gallon | Too small |
| 5 gallon | Too small |
| 10 gallon | Too small |
| 15 gallon | Too small |
| 20 gallon | Too small |
| 20 gallon long | Too small |
| 29 gallon | Too small |
| 40 gallon | Too small |
| 55 gallon | Too small |
| 75 gallon | Up to 14 |
| 125 gallon | Up to 23 |
Numbers are bioload limits only. Keep only one per tank.
What you need for rainbow sharks
Sized for a 75 gallon tank, the smallest common size that suits rainbow sharks. For a different tank or a mix of fish, use the stocking calculator for a list sized to your plan.
Tank and equipment
- 75 gallon aquarium (tank or kit) (opens Amazon in a new tab)Bigger tanks are more stable and easier for beginners. How to choose
- Aquarium stand for 75 gallons (opens Amazon in a new tab)The water alone weighs about 626 lb (284 kg), before glass, gravel and rock. How to choose
- 2 adjustable heaters, 100 W each (opens Amazon in a new tab)Holds about 75 °F (24 °C) in a room at 65 °F (18 °C). Two heaters keep the tank warm if one fails. How to choose
- Aquarium thermometer (opens Amazon in a new tab)Check it daily: heaters can fail stuck on or off. How to choose
- Hang-on-back filter rated 300–450 GPH (opens Amazon in a new tab)Community tank: 4–6 times the tank volume per hour. How to choose
- About 100 lb of aquarium gravel (opens Amazon in a new tab)Enough for a layer about 2 in (5 cm) deep. Smooth gravel suits most community fish. How to choose
- Water conditioner (dechlorinator) (opens Amazon in a new tab)Removes chlorine and chloramine from tap water. Seachem Prime is a popular, concentrated choice. How to choose
- Liquid test kit (ammonia, nitrite, nitrate, pH) (opens Amazon in a new tab)Liquid kits are more accurate than strips. The API Freshwater Master Test Kit is the common choice. How to choose
- Gravel vacuum (siphon) (opens Amazon in a new tab)Cleans the gravel and does the water change in one go. How to choose
- LED aquarium light, about 48 in long (opens Amazon in a new tab)Match the light to the tank length. Basic LEDs grow easy plants. How to choose
Food and extras for rainbow sharks
- Sinking pellets or wafers (opens Amazon in a new tab)Bottom feeders need food that reaches the floor.
- Caves and hides (opens Amazon in a new tab)Gives shy and territorial fish their own space.
- Tight-fitting lid for a 75 gallon tank (opens Amazon in a new tab)Rainbow shark can jump out of an open tank.
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Water parameters
Aim for 22–26°C (72–79°F), pH 6.5–7.5 and moderately soft to moderately hard water (about 5–12 dGH). Stable, clean, well-oxygenated water with gentle current keeps it healthy. Do partial water changes every week.
Best tank mates for rainbow sharks
These popular species share rainbow sharks' water needs and temperament. See the full list of 35 good matches.
Betta fish
6.5 cm (2.6 in) · 24–28°C (75–82°F)
Nerite snail
2.5 cm (1 in) · 22–27°C (72–81°F)
Dwarf gourami
7.5 cm (3 in) · 24–28°C (75–82°F)
Angelfish
15 cm (5.9 in) · 24–29°C (75–84°F)
Tiger barb
7 cm (2.8 in) · 22–27°C (72–81°F)
Oscar
30 cm (11.8 in) · 23–27°C (73–81°F)
Assassin snail
2.5 cm (1 in) · 22–27°C (72–81°F)
Ramshorn snail
2 cm (0.8 in) · 21–27°C (70–81°F)
Avoid keeping rainbow sharks with
- Cherry shrimp: Rainbow shark eats small shrimp like cherry shrimp.
- Discus: They need different temperatures: Rainbow shark 22–26°C (72–79°F), discus 28–30°C (82–86°F).
- Electric yellow cichlid: Electric yellow cichlid is a Lake Malawi cichlid. It needs a Lake Malawi tank: hard, alkaline water (pH 7.5–8.5), plenty of rockwork and other cichlids from the same lake. Rainbow sharks don't belong in that setup.
- German blue ram: They need different temperatures: Rainbow shark 22–26°C (72–79°F), german blue ram 27–30°C (81–86°F).
- Pea puffer: Pea puffer is best kept in a species-only tank.
- Peacock cichlid: Peacock cichlid is a Lake Malawi cichlid. It needs a Lake Malawi tank: hard, alkaline water (pH 7.5–8.5), plenty of rockwork and other cichlids from the same lake. Rainbow sharks don't belong in that setup.
Feeding
It grazes algae and biofilm but needs a full diet too. Feed sinking pellets or algae wafers daily, and offer frozen bloodworms, brine shrimp or daphnia a few times a week. Blanched zucchini, cucumber, peas and spinach make good extras.
Behavior
Juveniles are fairly calm, but adults get territorial and chase fish that use the bottom or look similar. Keep only one per tank, and never with red-tail sharks or algae eaters like flying foxes, Siamese algae eaters or Chinese algae eaters. Fast mid- and top-water fish such as danios, barbs, rainbowfish and larger rasboras make good company.
Breeding
Very rarely bred in home aquariums. Commercial farms produce them with hormone injections, including the albino and GloFish forms. Mature females are thicker-bodied than males, but juveniles can't be sexed.
Tips from experienced keepers
- Keep one per tank. Two rainbow sharks will fight in all but huge aquariums.
- Never combine it with red-tail sharks or other shark-shaped algae eaters.
- Add it as the last fish, after your other fish have settled in.
- GloFish sharks are the same species and need the same tank size as regular rainbow sharks.
- Give it a cave of its own and plenty of visual barriers so tankmates can escape.
Frequently asked questions
Can rainbow sharks live together?
Not in normal home aquariums. They are very territorial toward each other, and one will chase the other nonstop. Keep a single rainbow shark per tank.
What size tank does a rainbow shark need?
For one fish, at least 4 ft (120 cm) long and 18 in (45 cm) front to back, such as a standard 75-gallon (284 L). Length and width matter most, because it needs a large territory and room to swim.
Is a GloFish shark the same as a rainbow shark?
Yes. GloFish sharks are rainbow sharks that have been genetically modified to glow. They grow to about 6 inches (15 cm) and need the same care, tank size and one-per-tank rule.
Sources
We checked these references when writing this page. Values are for healthy long-term keeping, not survival limits. Last reviewed 2026-10-13. See our editorial policy.