How old be for you can put your baby fish in with your adult fish?

It's generally recommended to wait until baby fish, or fry, are at least 1-2 inches long before introducing them to adult fish. This size helps ensure that they are less likely to be seen as prey by larger fish. Additionally, it's important to consider the temperament and compatibility of the adult fish species to ensure a safe environment for the young fish. Always monitor their interactions when first introducing them.