Trumpetfish (Aulostomidae) are very amusing fish for the aquarium, but they do require a very large swimming area of 1000+ liters without pillars or similar obstructions, whilst still having places to hide.
Trumpetfish are predatory fish, that will mostly go after small fish, but crustaceans are also part of their diet. Trumpetfish have a fun personality, and will become attached to the aquarist over time.
They must have live food to begin with, small guppies for example, and can then slowly be introduced to small pieces of frozen fish and crustaceans.
One should avoid having larger predatory fish and aggressive Damsels and Wrasses as well as Triggerfish and Pufferfish when keeping Trumpetfish. Small ones can be kept together, but they do not often get along when becoming larger.