African dwarf frogs, snails and ghost shrimp, due to their unique characteristics, are all compatible tank mates for the betta. Other fish may be compatible depending upon the temperament of the individual betta. In general, avoid colorful fish, fish that are fin nippers, fish that live in brackish water, and fish that grow too large and overwhelm the tank space.
The African dwarf frog, due to its complete lack of resemblance to a fish, poses no threat to the betta. The betta should generally ignore the frog. Care must be taken to ensure the frog receives enough food, as the betta often eats his food and that of the slower frog.
Snails are protected from the attack of the betta by their hard shells. They are also excellent scavengers, keeping the water clean. If a snail is present in the tank, use caution when treating a sick betta. Copper in medicines may harm the snail. Move the betta to another tank before treatment.
Ghost shrimp are small enough to hide from the betta, and their clear color makes them almost impossible for the betta to see. Provide rocks or vegetation in the tank as good hiding locations for the shrimp.
Bettas are very territorial. Male fish should never be placed in the same tank, though females can coexist. When housing females together, odd groups work best, allowing the group to establish a hierarchy.