Feeding and growth rates for triploid grass carp as influenced by size andwater temperature

Thirty feeding trials were conducted using triploid grass carp (Ctenopharyn godon idella Val.) fed hydrilla (Hydrilla verticillata Royle) to establish feeding and growth rates as a function of fish size and water temperature. Size of fish ranged from 0.2 to 9.1 kg and water temperatures ranged from 1 7 to 27 C. Feeding trials consisted of fish and hydrilla housed in 4 m(3) w ire mesh cages suspended at weekly intervals in an experimental pond. Utili zing pre- and post-weights of fish and hydrilla, weight gain, relative and absolute feeding rates, and feeding efficiency were found to increase with increasing water temperatures. Relative and absolute feeding rates for 0.2 - 0.4 kg fish at 17 C were approximately 25% of that for similar sized fish at 27 C. Above 25 C, these small fish consumed their body weight per day o f hydrilla. While relative feeding rates (gm hydrilla/gm fish/day) declined with increase in fish size (at constant temperature), this was not the pat tern for absolute feeding rates (gm hydrilla/fish/day) where consumption ra tes ranged from 750 to 1200 gm hydrilla/day for fish weighing more than 1 k g.