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Filefishes

Critter Spotlight: Acreichthys tomentosus

Photo Credit: John Randall

These fishes belong in the Order Tetraodontiformes and Suborder Tetraodontoidei as members of the Family Monacanthidae (Filefishes) consisting of 31 genera, and 95 species. Filefishes somewhat resemble triggerfishes, with compressed bodies and a somewhat leaf-shaped body. They, as do triggerfishes, have an elongated first dorsal fin that can be erected when needed, however, their tail is not used for moving them forward. To discourage predators they can raise their first dorsal fin and/or grind their front teeth, i.e., incisors, producing a low-pitched growling sound. They are slow movers, do not do well in aquariums with swift water movement, and have extremely abrasive skin. They are sometimes called "leatherjackets" because of their skin texture. These omnivores are found in seagrass beds, where they consume plant material and any associated invertebrate they can find. Some species feed on sponges, coral polyps and/or gorgonians.

Their tough skin is covered with small scales and because of its rough sandpaper texture; they are sometimes called "Leatherjackets." In fact, in olden days their skin was used as sandpaper to finish wooden boats. Some are also called Foolfish because of an elongated snout, or Shinglefish because of skin texture. As for the snout, its somewhat tapered on most species, yet more so on others, and their eyes are located high on the head. They use their soft, mainly second dorsal and anal fins for swimming, therefore, are weak swimmers relying more on camouflage to avoid predation than their swimming capabilities. Some species are brightly colored, while others tend to blend in with the surrounding environment, with some having body filaments helping to imitate the weedy areas they call home, such as the Tasseled Filefish Chaetoderma pencilligera. Some also seem to have the capability to somewhat change body color to match surroundings.

These omnivores are generally found in shallow water, inhabiting depths of no more than 100 feet (30 m) and often inhabiting slow-flow reef areas where different types of algae exist, e.g., macroalgae, microalgae, seagrass, and/or coralline, which become part of their diet. Also on the menu are sponges, bryozoans, hydrozoans, coral polyps, gorgonians, tunicates and to a lesser degree, polychaete worms, small bivalves, snails, amphipods, urchins, and shrimp. Most have a body length of 4 - 12 inches (10 - 30 cm), but there is one species, the Scrawled Filefish, Aluterus scriptus that reaches 3 feet (1 m) in length, which is found in all tropical seas.

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