Notes on Native FisKes in Aquaria 



LEON L. PRAT 



Field Museum of Matural History 





For a number of years I have main- 

 tained a small aquarium or two on the 

 back of a table at my place of employ- 

 ment. A few seasons ago, in June, I 

 netted some fishes from a body of water 

 adjacent to the building. With the rubble 

 brought by the net from the bottom of 

 the pool were pieces of mussel shell and 

 pebbles, which I kept to add to the col- 

 lection at the bottom of my aquarium. 



Large-mouth black bass were nestling 

 along the shore of the pool, but I didn't 

 suspect I had taken eggs until several 

 days later, when I noticed half a dozen 

 newly-hatched babies moving uncertainly 

 about over the bottom. They were too 

 small to identify, but I suspected imme- 

 diately that they were bass. Each con- 

 sisted principally of a pair of goggle eyes, 

 a stomach attached below and a little to 

 the rear, and a pointed, apparently finless 

 tail. The tail was held curved around 

 at one side, except when the owner 

 wanted to get somewhere, when it was 

 energetically flipped backward to produce 

 forward motion. 



At this time there were countless 

 minute, whitish creatures dodging about 

 over the bottom and through the plants. 

 To these the baby fish turned their atten- 

 tion, seeming to depend upon them for 

 food at this stage of their career. In a 

 few days the little fish, which at first 

 were scarcely more than one-sixteenth of 

 an inch in length, began to straighten 

 their oddly-curved tails. During the 

 same time the yolk-sac was absorbed, 

 their mouths became larger and the fins 

 began to take shape and become visible. 



After three weeks they exhibited the 

 form and markings of the species, though 

 they were not more than a fourth of an 

 inch long. 



Soon a rather surprising thing hap- 

 pened. The baby bass turned cannibals. 

 The larger and stronger ones quickly 

 swallowed the smaller, afterward going 

 slowly about, rolling their eyes wisely, 



with the tail-fins of their brothers and 

 sisters protruding from their mouths. In 

 a few days but two remained. There 

 was but slight difference in size. When 

 I came in one morning one was gone. 

 Carefully I watched the survivor and, 

 sure enough, there was the bulging belly 

 and the tell-tale caudal fin sticking out 

 of his mouth. In outline he resembled 

 a mature bass. He was paunchy and 

 full-throated, just like many an old "crab- 

 cracker" that has fallen to my rod. It 

 was laughable. There swam the lordly 

 little savage, sole proprietor and tenant 

 of the tank, ruthless destroyer of his kin 



