Percopsidae is a family of fish in the order Percopsiformes

Percopsiformes

Percopsiformes is a small order of ray-finned fish, comprising the trout-perch and its allies. It contains just nine species, grouped into three families....

. Its living members are two North American fresh water species of the genus Percopsis, trout-perch Percopsis omiscomaycus (Walbaum

Johann Julius Walbaum

Johann Julius Walbaum was a physician, naturalist and taxonomist. He was the first to describe many previously unknown species from remote parts of the globe, such as the Great Barracuda , the Chum salmon from the Kamchatka River in Siberia, and the curimatá-pacú Johann Julius Walbaum (30 June...

 1792) and sand roller Percopsis transmontana (Eigenmann

Rosa Smith Eigenmann

Rosa Smith Eigenmann was the first notable female ichthyologist; first publishing in her own right, she later collaborated with her husband Carl H. Eigenmann, and some 150 species of fish are today credited "Eigenmann & Eigenmann" as a result.She was born in Monmouth, Illinois, the last of nine...

 & Eigenmann

Carl H. Eigenmann

Carl H. Eigenmann was an ichthyologist who, along with his wife Rosa Smith Eigenmann, described many of the fishes of North America and South America for the first time....

 1892).

They are small fish with weak fin spines, and an adipose fin similar to those of trout

Trout

Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

s. They feed on insects and small crustaceans.

Trout-perch

Trout perch are silvery-transparent in appearance. Specimens found in the US range from 76-102 mm while ones found in Canada can get as big as 152 millimetres (6 in). These fish live 3-4 years in shallow lakes and streams, hiding among rocks. They survive on chironomids

Chironomidae

Chironomidae are a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae...

, mayflies

Mayfly

Mayflies are insects which belong to the Order Ephemeroptera . They have been placed into an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies...

, amphipods

Amphipoda

Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. The name amphipoda means "different-footed", and refers to the different forms of appendages, unlike isopods, where all the legs are alike. Of the 7,000 species, 5,500 are classified...

, and small fish.

Sand roller

Similar in appearance to trout-perch, although shorter and stubbier, sand rollers grow up to 9.6 cm and live up to 6 years in slow-moving, sandy-bottomed streams and rivers among vegetation. Their diet includes flies

Diptera

Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...

 and Trichoptera

Trichoptera

The caddisflies are an order, Trichoptera, of insects with approximately 12,000 described species. Also called sedge-flies or rail-flies, they are small moth-like insects having two pairs of hairy membranous wings...

, although juveniles also have been known to eat crustacean zooplankton

Plankton

Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

.