Thing is a small 1-2 inch trigger will fast grow into a 10-24 inch trigger. They don't make 'em dwarf. They don't stay small. They grow. Fast.
Any trigger at all should be raised and kept in at least 60 gallons.
Providing the Proper Habitat: Triggerfish are bottom dwellers and usually live in the shallower, in shore areas of coral reefs. They are very active fish and need plenty of room to move around. They should only be kept in larger aquariums. Be sure to learn about any particular type of Trigger you want to purchase. Remember, some species grow to a very large size of up to 14 or 16 inches. It is best to provide these fish with plenty of rocks, stones, or coral formations to hide in. The more objects for them to hide around, behind or under, the better. Ample cover gives the other tank inhabitants a happy, safe feeling environment, as well helps to reduce conflicts and aggression in the community.