When Can Baby Fish Be Welcomed Into a Tank With Adult Fish?

Baby fish or fry are the most common fish sold in pet stores, according to "Freshwater Aquariums for Dummies." But even if you are breeding fish, the fry may never be able to go into a tank with adult fish, depending on the species.

  1. Types

    • Some species of fish, such as the oscar or velvet cichlid, will eat any smaller fish. Fry will begin to do this even at a small size. Some fish like the male betta will not fight with or kill other fish except for other male bettas.

    Size

    • It is best to keep fish that are about the same size so that the larger fish are not tempted to eat the smaller fish. Even the fry's parents will eat the fry if given a chance. This not only feeds the parents but increases their fertility.

    Considerations

    • Before adding younger and smaller fish to a tank with adult fish, be sure there are plenty of places for the smaller fish to hide. Small fish that school, such as neon tetras, give off an illusion that they are one large fish. Get about six of these small fish when adding them to a tank filled with peaceful adult species.