414 



Z(X)LOGICAI, SOCIETY BULLETIN. 



It was apparently not more than a year 

 old and exhibited no fear of tlie ship's com- 

 pany, I'emaining in the boat until morning, 

 when it was driven out as the boat was hoisted 

 to tlie davits. 



NATURAL FOODS OE ERESH-AVATER 

 EISHES. 



THE keeping of fishes and other forms of 

 life in small aquaria is a wide-spread 

 practice. 



ProbabU' a majoritv of the letters received 

 at the Aquarium, from week to week, are 

 of inquiry respecting the care of fishes, 

 newts, frogs, turtles and tlie like. Leaflets 

 of information on the care of goldfishes and 

 other aquatic creatures have been prepared 

 and printed for the purpose of facilitating 

 correspondence of this sort. 



The food of most of our game fishes con- 

 sists chiefly of other fishes, which may at 

 times be their own young. Fishes in general 

 are feeders on animal life, and their food sup- 

 ply includes practically f/(t'K7ioZr«(/Hrt^(ff««»«. 



Fishes may be described as not only pis- 

 civorous and insectivorous, but as feeders on 

 crustaceans, mollusks and worms. Plants do 

 not constitute much of their food, although 

 a few kinds feed freely on them, such as buf- 

 falo-fishes, carps and minnows. The young 

 of many fishes nibble at tender plant shoots. 



Some fishes are mud diggers, while others 

 are downright scavengers. Rats, mice and 

 kittens have (very appropriated) been found 

 in the stomachs of catfishes, and mice have 

 been found in black bass, according to Pro- 

 fessor Forbes, who investigated the food 

 habits of many species in the ]Mississippi 

 Valley. A large pike would doubtless not 

 hesitate to swallow a young muskrat, just as 

 it does a young water-bird. 



Newts and salamanders are eaten by fishes 

 as well as frogs and tadpoles. The more 

 predator^' fishes may even kill the smaller 

 water snakes, and it is probable that young- 

 alligators have enemies among some of the 

 southern predatory fishes. 



Among the chiefly fish-eating fishes may 

 be mentioned pike, pickerel, muscallonge, 

 pike-perch, burbot, gar, black bass, channel 

 and mud-catfishes. 



Those taking fish food in moderate amount 



are represented by bream, blue-cheeked sunfish, 

 mudfish, white-bass, rock-bass and crappie. 



Fishes which are piscivorous to a trivial 

 extent, are white perch, suckers, gizzard-shad, 

 spoonbill, the various darters, top minnows 

 and silversides, stickleback, mud-minnow, 

 stone-cats and common minnows. 



The fishes in general which are devoured 

 in the largest numbers, are the smaller and 

 more defenseless forms which occur in great- 

 est abundance, while the young are naturally 

 more readily eaten than the adults. The 

 whole minnow tribe contributes to the food 

 of the smaller fish caters. 



In the jMississippi region the gizzard-shad 

 constitutes forty per cent, of the food of the 

 wall-eyed pike, thirty per cent, that of the 

 black bass, half that of the pike and a third 

 that of the gars. 



^Mollusks, the snails, and mussels of various 

 species, large and small — are also important 

 as fish food. They form large proportions 

 of the food of catfishes, suckers, fresh-water 

 sheepshead and mudfish. 



About sixteen per cent, of the food of 

 perches, sunfishes, top-minnows and shiners 

 is molluscan in character. 



Fishes as a class feed largely on insects, 

 and the minnows and darters chiefly so. 



Insect food includes not only the aquatic 

 forms in their various larval and mature 

 stages, but also terrestrial insects cast into 

 the water in many ways. The larval forms 

 of neuropterous insects constitute about one- 

 sixth of the food of fishes. 



Crustaceans appear to be of even more im- 

 portance as fish food, the minute Entomos- 

 traca being the principal kinds. The cray- 

 fishes are also eaten. Worms and leeches 

 appear to be of comparatively little impor- 

 tance in the diet of fishes. 



In the minnow family, vegetable forms — 

 chiefly algae, make up about one-fourth of 

 the food. The food of adult fishes naturally 

 differs greatly from that of the young. The 

 question then as to what constitutes the food 

 of fishes may be answered : almost any living 

 animal forms from the icater, not too large 

 to be swallowed, due consideration being given 

 to the habits of the various species. 



In addition to natural foods, both alive and 

 dead, fishes in captivity will devour many 

 kinds of meats and prepared foods. 



