Rainbow Shark: Tank Size, Tank Mates and How Many to Keep

Rainbow sharks are dark fish with red fins. They are not real sharks, but they guard the bottom of the tank as if they were.

Adult size
5.9 in15 cm
Smallest tank
55 gallons208 liters
How many
One only
Temperature
72–81 °F22–27 °C
pH
6.5–7.8
Temperament
Semi-aggressive
Swims
On the bottom
Heater needed
Yes

What size tank does a rainbow shark need?

At least 55 gallons (208 liters). The smallest standard tank that works is the 55 gallon. A bigger tank is always easier to keep stable. We give the size for an adult fish, because the small fish in the shop will grow. Scientific name: Epalzeorhynchos frenatum.

How many rainbow sharks in each tank size?

This is how many each standard tank carries comfortably if rainbow sharks are the only fish in it. Share the tank with other species and the number goes down.

Keep one rainbow shark per tank, whatever the size. Of the common sizes, these are big enough: 55 gallon, 75 gallon, 125 gallon.

Check rainbow sharks against your own tank and other fish

Good to know

  • Keep one per tank. Two will fight over the floor.

Tank mates for rainbow sharks

These animals like the same water, are a safe size, and have a temper that fits. It is a match on paper: always watch new tankmates for the first week.

Poor matches

  • Neon tetra: Rainbow shark (about 6 in) can eat neon tetra (about 1.4 in).
  • Fancy goldfish: Goldfish do best with other fancy goldfish.
  • Oscar: Oscar is aggressive and much bigger. Rainbow shark would be bullied.
  • Molly: They need different water: Rainbow shark likes a pH of 6.5–7.8, molly likes 7.5–8.5.

Questions and answers

What size tank does a rainbow shark need?

At least 55 gallons (208 liters). The smallest standard tank that works is the 55 gallon. A bigger tank is always easier to keep stable.

How many rainbow sharks should be kept together?

Just one. Rainbow shark adults fight each other in a home tank.

Can rainbow sharks live in a 10 gallon tank?

No. Rainbow shark needs at least 55 gallons (208 liters), and grows to 6 in (15 cm), far too long for a 20 inch tank.

What temperature do rainbow sharks need?

72–81 °F (22–27 °C), with a pH of 6.5–7.8. In most homes that means a heater.

Can rainbow sharks live with a betta?

Usually, yes, in a tank of 55 gallons (208 liters) or more. They like the same water: 75–81 °F (24–27 °C). Every betta has its own temper, so watch closely for the first week and have a spare tank ready.

More fish

Adult size, tank size and water ranges follow the mainstream care consensus (Seriously Fish species profiles and FishBase maximum lengths). Where sources differ we use the more cautious figure. Stocking numbers come from our stocking calculator.