Some names and vocabulary to understand —
Ambush/Lie-in-wait predators: Primarily piscivores (fish eaters) whose body shape is well suited for ambushing fish. The shape is generally long and often torpedo shaped. The head is flattened and equipped with a large mouth filled with sharp teeth. The arrangement of the fins, give it the ability to launch itself at high speed from a nearly stationary position. The narrow frontal profile, coloring, and secretive behavior make them less visible to prey. (Examples: barracuda, needlefish, lingcod, and lizardfish).
Rover-predators: A streamlined (fusiform) body shape with a pointed, torpedo-shaped head, terminal mouth and forked tail. They typically have evenly distributed fins that provide stability and maneuverability and the ability to move fast and efficiently through the water. Constantly on the move, seeking out prey that they pursue and capture. (Examples: mackerel and bonito).
Bottom fish: Several different body shapes are included for bottom fish; most are flattened in one direction or another. Bottom rovers: A rover-predator-like body but the head tends to be flattened, the back humped, and with enlarged pectoral fins. May have fleshy, protrusible lips below the snout used to suck up plant and animal matter off the bottom. (Example: sturgeon) Many have small eyes and barbels (whiskers) equipped with taste buds to help find prey at night. (Example: croakers) Many sharks, with inferior mouths (under the head and behind the snout), flattened heads, and large pectoral fins are classified as bottom rovers. Bottom clingers: Mainly small fish with flattened heads and large pectoral fins that allow them to adhere to the bottom. (Examples: sculpins and gobies) Bottom hiders: They have more elongate bodies and smaller heads than clingers and lack clinging devices. (Example: blennies). Flatfish: Basically deep-bodied, laterally compressed fish that live with one side on the bottom; the mouth often assumes a peculiar twist to enable bottom feeding. Many live buried in the sand, darting up to catch unsuspected prey. (Examples: flounder, sole and halibut) Some are flattened dorsoventrally and move about by flapping or undulating their large pectoral fins; the mouth is completely ventral. (Examples: skates and rays).
Surface-oriented fish: Typically small in size, upward pointed mouth, flattened head with large eyes, uniform to deep body, and a dorsal fin placed toward the rear of the body. They capture plankton, bugs and small fish near the surface. Most are fresh or brackish-water fish but saltwater forms include halfbeaks and flying fish.
Deep-bodied fish: Laterally flattened (compressed) body with body depth one-third of standard length, long dorsal and anal fins with pectoral fins high on body. The mouth is usually small and protrusible, the eyes large, and the snout short. Well adapted for maneuvering in tight quarters (such as around piers), dense vegetation, or in tight schools of their own species. Most are bottom dwellers and many have strong spines for protection. (Examples: perch, opaleye, garibaldi, and rockfish.) Some open-water plankton feeders are also deep-bodied.
Eel-like fish: Elongate bodies, blunt or wedge-shaped heads, and tapering or rounded tails. Small fins if present, long dorsal and anal fins, and small or no scales. Well adapted for living in crevices and holes in rocky areas as well as making their way through areas of vegetation. (Examples: moray eel, wolf-eel and monkeyface prickleback)
Adapted from Fishes, An Introduction to Ichthyology by Peter B. Moyle and Joseph J. Cech, Jr
Additional names and vocabulary —
Diadromous: A fish that that travels between salt water and fresh water as part of its life cycle.
Anadromous: A fish that lives its adult life in salt water and migrates into fresh water to spawn. The term anadromous means “upward-running” since they migrate back up rivers from the sea.
Catadromous: A fish that lives its adult life in fresh water and migrates into salt water to spawn. The term catadromous means “downward running” since they migrate down the rivers to the sea.
Crepuscular: A fish that is primarily active during twilight, i.e., dawn and dusk.
Diurnal: A fish that is active during the daytime and rests at night.
Nocturnal: A fish that is most active at night.
