xununojc axd feeding 217 



beneficial in this regard. The amino acid requirements for catfish have not 

 been established, but appear to be similar to those for salmonids. 



Catfish feeds — or any feeds fed in extensive culrure — are classified as 

 either complete or supplemental diets. Complete feeds are formulated to 

 contain all the \"itamins. minerals, protein, and energ^" needed by the fist. 

 Usually these complete feeds contain 30 to -iO'i total crude protein, of 

 which fish meal may make up 10 to 25^': of the feed. Complete feeds are 

 more expensive than supplemental feeds. Complete feeds are fed to fry, 

 and also to larger fish raised intensively in race\*"ays, cages, or other 

 en\ixonments where the intake of natural feeds is restricted. 



Supplemental feeds are formulated to pro\ide additional protein, energy, 

 and other nutrients to fish utilizing natural food. Generally, the fish are 

 expected to eat natural food organisms to supply ifce essential growth fac- 

 tors absent in the feed. Usually supplemental feeds contain a lower level of 

 crude protein than complete feeds, and soybean meal is the principal pro- 

 tein source. 



Low stocking rates and low standing crops of fish result in more natural 

 food and protein being available to each fish. The above factors and oth- 

 ers, such as season, fish size, feeding rate, water temf>erature, oxygen lev- 

 els, and disease influence the dietary- protein levels required for maximum 

 efficiency in growth. Consequently, no one protein level in feeds "v*"ill meet 

 all conditions and it remains for the fish culturist to choose the feed viith a 

 protein level that \*ill satisfy' production needs. 



PROTEIN IN COOLW.\TER FISH FEEDS 



Feeding trials \*ith northern pike, chain pickerel, muskellunge, vt-alle\-e, 

 and the hybrid tiger muskellunge showed that the hybrid and. to a lesaer 

 degree, northern pike v^ill accept a dr\ pelleted, formulated feed. A 50'*- 

 protein e.xperimental feed Appendix F formulated specifically for cool- 

 water fish provided the highest survival and growth •with fingerlings. Trout 

 feeds and exf)erimental feeds that contain less protein were inadequate. 

 Therefore, ii appears that the protein requirement for the fingerlings of 

 these species is about 50*t of the feed. It is also noteworthy that 60-SO V of 

 the dietarx protein was supplied by animal protein sources in feeds that 

 proved satisfiactor>\ Only limited testing has been conducted on feeding 

 advemced fingerlings of coolwater species, but indications are that the pro- 

 tein level of the feed can be reduced. This follows the similar pattern for 

 trout and catfish. 



Car bo hydra U Rfquirfmrnts 



Carbohydrates are a major source of energy to man and domestic animals, 

 but not to salmonids or catfish. Onlv limited information is av^ailable on 



