Inhabits northern, and mountain and foothill streams, and oligotrophic lakes. Found in fast-flowing waters of coastal streams, rivers, inland lakes, usually on stony bottoms. Moves downstream to estuaries and tolerates brackish waters. Feeds on algae (diatoms, desmids, blue-green algae), polychaetes, crustaceans, aquatic insect larvae and nymphs (Ephemeroptera, Trichoptera, Plecoptera, Chironomidae), fish eggs and larvae.