[Ebook] Encyclopedia of Aquarium & Pond Fish – Directory of Marine Fish – Filefish
Closely related to the triggerfish, filefish are not so boisterous in aquarium surroundings as their cousins, nor as destructive. Most species are smaller than triggers, but they share with them the split configuration of the dorsal fin (the first part forms a spine used to anchor the fish in a cave). The ventral fin on the underside of the body is similarly modified, providing additional support.