Introduction to Australian Rainbow Fish: Rainbow fish are only distributed in the freshwater waters of Australia and New Guinea. These colorful, gregarious little fish can live in clear streams with fast currents, and can also inhabit surrounding areas. in disconnected, isolated ponds. Most rainbow fish do not have a fixed breeding season and can lay eggs throughout the year, but the number of eggs each time is small. Interestingly, their eggs have strange sticky threads that can adhere to aquatic plants. After 7 to 10 days, the young fish will hatch.