Question: how big do turquoise rainbow fish get?
Answer: General: The Turquoise Rainbowfish (Melanotaenia lacustris) is an endemic fish species of New Guinea. The Turquoise Rainbowfish will reach a length of four inches, and may live for eight years in captivity. Ideally, the Rainbowfish will behave most naturally in an aquarium larger than 55 gallons.