What Proportions of Male to Female Rainbow Fish Can Be Kept?

Rainbow fish are a relatively small class of tropical fish from the southern hemisphere. These are divided into numerous species, all renowned for their bright colors. The question of how many males and females you can keep in a single aquarium is likely to come up when selecting fish for a potential school. Keeping the right proportion of males to females can ensure brighter colors among your group of fish.

  1. School Size

    • Rainbow fish are natural schooling fish that are happy in groups of 10 to 15 individuals. You should keep at least six individuals in a single tank. Rainbow fish are naturally shy. If you keep fewer than six individuals, they may not school and may hide from the other fish in the tank.

    Bringing Out Color

    • Male rainbow fish will compete for female mates by displaying their colors more vibrantly than other males. Introducing a 2:1 ratio of males to females will create a competition among the tank's males, which will bring out their colors. Keeping all males or all females will result in duller color variations because of lack of competition.

    Spawning

    • A potential side effect of keeping a ratio of males and females together is that they may spawn. The females will lay eggs in floating plants like moss (but not having moss will not prevent spawning) and the male will fertilize them. The parents will eat the eggs, however, unless you transfer them to a separate tank where they can develop unhindered.

    Sexing

    • Rainbow fish have little to no physical sexual dimorphism with the exception that males may be slightly larger with brighter colors in adulthood. To ensure that you have a mix of males and females, purchase at least six individuals if buying from a pet store. Professional breeders may be able to better sex the fish, so purchasing from a breeder may be the best option to ensure an exact ratio.