الفهرس 
introduction
Results and observationsOnly 14 pages are availabe for public view
 |  | from | 204 |  |  |
| | | from | 204 | | |
Abstract
In Egypt, the need for increasing fish production is necessary in view of the high demand for fish as a relatively cheep source of animal protein. Tilapias are a major protein source in many of developing countries. As a result the demand for sufficient supply of fry and fingerlings of these species has recently picked up among fish pond operations. The present demand for the juveniles of tilapia can not be satisfied by the usual commercial fishing in natural waters. Consequently, man must help the nature in such respects through developing and creating efficient mean. Recent work in the seeding production of teleost fish indicates that management and larval rearing. Growth and survive of fish larvae are primarily dependent on feeding success and effective digestion and absorption of nutrients. Thyroxine, cortisol, growth hormone and prolactin are essential to regulate development and growth of fish larvae. Thyroid hormones are well known to induce changes in intestinal epithelial cells, particularly during metamorphosis of amphibians and marine fish larvae. Allmale populations of tilapias are usually preferred over mixed sex populations because of the faster growth rate exhibited of by males. 17 <U+F061> methyltestosterone can produce a monosxes population by sex reversal and permit farmers to achieve high yields of fish.