The diet of most pufferfish consists of algae and invertebrates. Larger members of the species utilize their strong teeth to crack open the shells of clams and shellfish.
Wild pufferfish constantly crunch on the shells of their prey, which erodes their teeth. To compensate for this, pufferfish teeth constantly grow. If a pufferfish does not have access to animals in shells, its teeth may grow too long and inhibit the ability of the fish to open its mouths to eat. For pufferfish kept in aquariums, the diet should include unshelled, whole creatures including snails, prawns and small crabs to prevent this problem.