Hundreds of puffer fish species exist, and puffers from different environments have differing compatability issues, requiring some care when selecting tank mates. Puffers can be aggressive and have sharp beaks. However, a few puffers make good candidates for community-style tanks.
Saltwater Puffer Fish
Saltwater puffer fish tend to get along with sturdy, outgoing tank mates of similar size. Keep in mind, this size varies based on the specific species of puffer. Depending on their size, marine puffers can get along easily with lionfish, dwarf lionfish, angelfish and tangs. Avoid shy or slow-swimming fish. All puffer fish have sharp, beaklike jaws adapted for crushing invertebrates. This makes saltwater puffers poorly suited for reef tanks or for sharing any aquarium with invertebrates.
Brackish Puffer Fish
Brackish water has some salt in it, but it has less salt than full-strength seawater has. Many popular so-called freshwater puffer fish are actually from brackish waters. Research your fish before you buy to make sure you have the right setup. Brackish water puffers are typically aggressive, but not extremely. They can share a tank with any fish who has the same water requirements and is not passive.
Larger Freshwater Pufferfish
Unfortunately, most true freshwater puffers get very aggressive. Most require a dedicated species tank without other fish, since they will attack other fish. Some species of freshwater puffer fish will even attack their own species in all but the largest aquariums. Do not try to keep such species without researching it first.
Dwarf Freshwater Pufferfish
Dwarf freshwater puffer fish are the oddball of the freshwater puffers. They grow to less than an inch long and typically live in schools. Additionally, they get along with most other fish. You must take their small size into consideration, since they could fall prey to larger fish, and fast-swimming aggressive fish can easily out-compete them for food. However, the only concern with the dwarf puffer's temperament is that these small fish like to nip at long-finned fish like bettas. Unlike other freshwater puffers, these are very mild fish.