ANNOTATED LIST OF FISHES 



1 127 



In their feeding habits the two common crappies are very similar, as in this region both 

 appear to subsist largely upon small fish; and in this respect they are a distinct aid to the mosquito, 

 in that their principal food, according to the contents of 51 stomachs examined, consists of the top 

 minnow, Gambusia, which in the South is the most effective natural enemy of the mosquito. The 

 fish diet was supplemented largely by the water boatman, Corixa, and to a less extent by the 

 shrimp, Palxmonetes exilipes. The young white crappie 

 utilized copepods almost exclusively until an approximate 

 total length of 90 millimeters was attained, when a rather 

 definite transfer to the adult diet was noted. The young 

 black crappie, on the other hand, also utilized the minute 

 crustaceans, but was frequently found to have taken fish 

 when it had attained a length of only 70 millimeters. 

 In addition to the copepods, the young crappie had 

 utilized to a much less extent, also, Cladocera and phyl- 

 lopods. 



The spawning season at Havana is in May, as indi- 

 cated by Forbes and Richardson (1908, p. 239) . A crappie 

 135 millimeters long, taken June 16, 1925, contained ap- 

 proximately 1,200 ripe eggs, which, no doubt, is below the 

 average production, as this fish was a comparatively small 



Fig. 5. — Outline of head of Pomoxis annularis. 

 From a specimen 145 millimeters long 



Ninety-four specimens, ranging in length from 55 to 360 millimeters (2}4 to 14^ inches), 

 were preserved. These were collected at three localities: Borrow pit on the Itta Bena Road, 

 slough at Money, and borrow pit at Craigside. 



30. Pomoxis sparoides (Lacepede) 

 Black crappie; Calico bass 



Labrus sparoides Lacepede, Hist. Nat. Poiss., Ill, 1802, p. 517. 



In general, as shown in the key, this species has a deeper body than annularis, less deeply 

 concave dorsal profile, more oblique mouth, and in color it generally differs in being more definitely 

 spotted, none of the dark markings being arranged so as to form crossbars, as is often the case in 

 annularis, and the spots usually are extended on the anal fin. In annularis the interradial mem- 

 branes of the anal fin frequently are dusky, but this color is not broken up into spots as in sparoides. 



In this region the black crappie simulates the white crappie in its fish and insect diet, as shown 

 by a comparison of the food contents of 42 stomachs of the former and 51 stomachs of the latter. 

 It thrives, however, when small fish are not available and under these circumstances was found to 

 utilize the plankton crustaceans, including copepods, Cladocera, and ostracods, in lieu of the small 

 fish. The insect component of the diet, which consisted largely of the water boatman, Corixa, 

 appeared never to be lacking. The young black crappie apparently subsists almost entirely upon 

 copepods and under normal conditions changes to the adult diet when it approximates 80 milli- 

 meters in length. In all three species listed the stomach is large and the length of the intestine is 

 contained about three and one-half times in the total length of the fish. 



On account of their frequency and predatory habits, these fish locally are by far the most 

 formidable enemy of the mosquito-destroying minnow, Gambusia, which in this region forms the 

 basis for the fish diet of the crappies. In addition to Gambusia, small bass, sunfish, and the young 

 of their own kind were found to have been ingested. 



In an attempt to determine whether the young crappie was of value as a mosquito-larvae 

 eradicator, 100 fish, approximating 1 inch in length, were confined to an area of 120 square feet in 

 a borrow pit, and this inclosure was compared with another in which no fish were present. In 

 this instance the results were entirely negative, as the young crappie apparently ignored the 

 numerous larval mosquitoes during the whole course of the experiment, which was conducted over 

 a period of two months. 



