slender, streamlined shape, large mouth that extends slightly past rear margin of eye when closed; greenish sides with dark mottlings and golden-shaded reflections; broad dark stripe along side, but more broken and uneven than on largemouth bass
Coralville reservoir and Iowa River near the reservoir
aquatic insects, crustaceans, crayfish, and fish
Spotted bass are common in the southern latitudes of this continent, and are not a native species in Iowa. This species was introduced into the Middle Raccoon River and Whitebreast Creek in 1963 from fingerling produced at the Lake Wapello hatchery. It is possible they still exist in these two streams, but there have been no recent identifications. In 1969 and 1970 spotted bass fingerlings were stocked into Lake Macbride where they have established populations that are reproducing. Spotted bass have been recently collected in Coralville Reservoir, and they probably exist in the Iowa River near the reservoir.
The spotted bass is a slender, streamlined-shaped sunfish with a large mouth, and the upper jaw extends slightly past the rear margin of the eye when the mouth is closed. The sides are greenish in color with darker mottlings and golden-shaded reflections. There is a broad dark continuous stripe along the side, but the margins of this stripe are noticeably more broken and uneven than in largemouth bass. This stripe may become indistinct in large fish or in fish from turbid water. The lower sides have spots arranged in distinct rows that form a series of horizontal stripes. The tail fin in young bass has a black vertical bar that separates the yellowish-orange fin base from a whitish fringe along the rear margin of the fin. The dark bar usually forms a black spot in the middle of the tail fin. The pyloric caeca of spotted bass are not forked, like those of smallmouth bass.
Spotted bass fry consume copepods and cladocerans, graduating to insects and eventually to fish and crayfish. Their habits are nearly between those of smallmouth and largemouth bass. Fish comprised 56 percent of the diet of spotted bass in some food habits studies. Other studies indicate spotted bass are not as predatory as largemouth, consuming about one-half as much fish.
Habits of the spotted bass are similar to those of smallmouth bass, except more secretive. Spotted bass spawn mainly in river tributaries and along rocky edges in lakes. They prefer rocky habitat for nest building, which are quite small in size, less than one-third the size of other black bass nests. Deposition and the development of eggs is comparable to that of smallmouth at about the same temperature. Sac fry schools leave the nest in 8-9 days and the male is quiet, attentive and protective.
Growth of spotted bass is nearly equal that of largemouth bass, but after the first year of life, growth rate becomes slightly less than largemouth bass in Iowa. Spotted bass in Lake Macbride reach about 3 3/4 inches in the first year, 7 inches by the end of the second year, 10 inches in the third year and 12 inches in the fourth year. Maximum weight of this species in Iowa is about 3 pounds.