Lionfish vary in size according to their species, and they need saltwater habitats large enough to sustain them. Though they can be fed live feeder food at first, eventually they need fresh and frozen seafood. Care must be taken to choose tank mates that lionfish do not consume. It is important to avoid touching lionfish, as their venomous stings cause serious injuries.

Smaller lionfish such as dwarf lions do well in tanks of 30 to 50 gallons, but larger lionfish need tanks of at least 75 to 100 gallons. Lionfish do not need artificial lighting, as they feed at dusk or dawn and prefer to have places they can hide in the shadows. Lionfish do well in reef aquariums, as they do not harm coral or sponges, but they feed on crustaceans such as cleaner shrimp and hermit crabs. Lionfish prey on smaller fish, so tank mates need to be large enough so they cannot be swallowed. If the tank is large enough, sometimes lionfish peacefully coexist with each other, but if they become aggressive, they must be separated. Freshwater live feeder fish such as goldfish, guppies and ghost shrimp do not contain the fatty acids that saltwater predators need. A diet of seafood is best, but the chunks must be impaled on a chopstick or toothpick and wiggled to simulate live prey.

The spines of lionfish contain toxic venom. Aquarists are most often stung when cleaning tanks or moving fish from one tank to another. Symptoms include extreme pain, weakness, nausea, vomiting, shortness of breath, fever and chest or abdominal pain. A sting can be immersed in nonscalding hot water for about half an hour until the pain subsides, but if more serious symptoms persist, the victim should be taken to the ER.