Missouri fishes inhabit many different aquatic habitats—from riffles and pools of large rivers and small streams to natural and artificial lakes, ponds and oxbows. Each species has adapted to survive in one or more of these habitats, but few can survive in all habitats.
Traits that allow a species to live in a particular habitat can be adaptations in temperature tolerance, salt tolerance, the ability to breath air when needed, and in body form.
Adaptations of a fish’s body that allow a species to survive in different habitats include shape of the body, fin location and mouth size and orientation.
In general, body forms of Missouri fishes can be grouped into seven different categories: rover predator, lie-in-wait predator, deep-bodied fish, eel-like fish, bottom rover, bottom clinger and surface-oriented fish.
Temperate and black basses (like the largemouth bass illustrated above), trout and walleye are examples of fish with body shapes adapted to a rover-predator lifestyle. Their bodies are elongate, their fins are distributed around the body evenly, their head is pointed with a relatively large mouth at the tip, and they usually have a forked tail, an indicator of a fast swimmer. This type of fish roves through several types of habitats from still to swift waters, and uses speed to catch prey. Many of our favorite Missouri game fish are rover predators.
Pickerel (illustrated above) and gar are Missouri species with the lie-in-wait predator body adaptation. Their bodies are elongate, their fins are moved back on the body to provide thrust for chasing prey, their head is pointed and flattened on top, and they have a mouth full of teeth at the tip. This type of fish will lie hidden by cover in still or slow moving waters and dart out to snap up prey.
Many sunfish (like the bluegill illustrated above) and buffalofish species exhibit the deep-bodied form. Deep-bodied fishes are flattened laterally and have long dorsal and anal fins. Their pectoral and pelvic fins are located high on the body. This type of fish mainly occurs in still waters and are adapted for maneuverability in heavy cover. They typically feed from the bottom or pick slow-moving prey from the water column.
American eel (illustrated above) and lampreys are examples of Missouri eel-like fish. They have very elongate bodies with reduced pelvic and pectoral fins, very long anal and dorsal fins, and unforked tails. This type of fish occurs in still to moderately swift waters and is adapted for maneuverability in tight places and burrowing in soft substrates. Eels typically sneak up on prey, and lampreys filter food from the bottom with some species becoming parasitic as adults.
Sculpins (like the banded sculpin illustrated above) and many darter species are adapted as bottom clingers. They tend to have flattened heads and large pectoral fins that are angled to keep the fish on the bottom in swift currents. This type of fish occurs in the swift water of riffles where they pick invertebrates from the rocks
Many Missouri catfish and suckers (like the golden redhorse illustrated above) are adapted as bottom rovers. These species have a body shape similar to the rover predator except the back is humped, the head is flattened, and the pectoral fins are enlarged. This type of fish occurs in still to swift waters and uses speed to avoid predators. The mouths of bottom rovers are placed in several different positions depending on their feeding style. Omnivours like catfish have a terminal mouth that allows them to take prey if the opportunity arises, generalist bottom feeders like many suckers have a subterminal mouth, and bottom feeders like carp have ventral mouths with protrusible lips for sucking ooze. Many bottom rovers also have well developed barbels for locating food by feel.
Missouri’s topminnows (like the blackstripe topminnow illustrated above) and studfish are surface-oriented species. They are typically small-bodied and have a flat head with upturned mouth. Their dorsal fin is moved back on their body. This type of fish occurs in still waters and feeds on organisms that fall in the water. Many surface-oriented species can survive in deoxygenated waters by breathing the surface layer of water that always contains some oxygen.
Fish illustrations by Joseph R Tomelleri. Used with permission.