139 
FISHES OF CHESAPEAKE BAY 
trals golden; pectorals dusky yellow. When not in breeding condition the colors of the male fade 
somewhat. The young are mostly grayish and bear dark cross bars, which vary greatly in number. 
The color markings differentiating the sexes usually become evident when the fish have attained 
a length of 1^ to inches. A large variation in the intensity of color exists among specimens, 
depending upon the environment in which they are taken, color adaptation being developed to a 
considerable degree. 
Numerous specimens of this species taken in many localities, ranging in length from 20 to 123 
millimeters (% to 4^ inches), were preserved. This species is recognized by its chubby form, short 
and broad snout, and by the coloration. The smaller, brightly colored males are sometimes difficult 
to separate from the adult males of F. lucise. When the color can not be relied upon for identifica- 
tion, the length and position of the dorsal fin must be taken into consideration. The dorsal fin in 
the present species consists of 11 or 12 rays and is inserted over or a little in advance of the origin 
of the anal. In F. lucise the dorsal fin has eight rays and is inserted a little posterior to the origin 
of the anal. 
This fish feeds on a large variety of foods. Among the contents of 48 stomachs examined, the 
following foods were found: Small crustaceans, small mollusks, annelid worms, insects, small fish, 
and vegetable matter, such as blades of grass, bits of roots, algae, and seeds. A considerable amount 
of sand also was present in some of the specimens examined, but this may have been taken inci- 
dently in the capture of foods. 
Spawning takes place from April to August, and it seems probable that one female may produce 
several broods of eggs during one summer. The ovary is single and the number of eggs produced 
varies greatly among specimens. The largest number of ova of one size found among several dozen 
specimens examined was taken from a female 98 millimeters in length, which contained 460. The 
eggs of one brood are of uniform size, rather large, and spherical when mature, measuring about 
2 millimeters in diameter. Sexual maturity is attained by the female when it has reached a length 
of approximately inches, and the male may be sexually mature when 1J4 inches long. The 
largest fish taken during the present investigation was a female 4% inches long, which represents 
the maximum size attained by the species, and the largest male was 4 inches long. The females 
reach a somewhat larger size than the males, the difference in the average length between the sexes 
among the adult fish being about one-half inch. 
This fish is very common in the shallow, brackish-water coves and inlets of Chesapeake Bay, 
ascending streams to fresh water. It was rarely taken in strictly salt water, the species being 
more fresh than brackish water in its habits than F. majalis, athough the habitats of the two overlap. 
F. heteroclitus is found on many kinds of bottom, but it prefers mud, one of its common names 
being “mud dabbler,” in allusion to its mud-frequenting habit. Chidester (1920, pp. 551-557), 
who made a special study of the habits of F. heteroclitus on the Bonhamptown Marshes, N. J., and 
at Woods Hole, Mass., states that a spring migration from the mouth of the Raritan River to the 
brackish and fresh waters takes place, and that when cold weather comes they again retire to the 
deeper waters. Those caught in pools burrowed in the mud upon the approach of cold weather. 
During the winter fish were found burrowed in the mud at a depth of 6 to 8 inches. 
