Comparison of rotifer Brachionus plicatilis as a choice of live feed with dry feed in rearing Coregonus lavaretus fry

This experiment, designed for the first time in the Middle East region to sustain Coregonus lavaretus production, examined the efficacy of a live organism ( Brachionus plicatilis ), an artificial diet (48% crude protein) and a mixed feed for the first 3 month of rearing fry. Nine rearing cages were floated on the surface of a natural pond supplied with hyporheic-zone river water, each containing 150 numbers of white fish fry, where they were treated with each of the three diets in triplicates. The fry were fed eight times daily starting at the onset of exogenous feeding. Results showed that fry utilized live organisms more efficiently than the artificial and mixed diets. Rotifer-fed group consistently showed higher growth rate during the entire experiment. Length increment (29.6 mm), weight gain (572.3 mg) after 12 weeks of feeding were higher ( P  < 0.05) in this group. Also, their mean weekly specific growth rate (4.97% day⁻¹) was the highest and feed conversion rate (2.97) was the lowest among all treatments. Survival rates of the fry declined from 75% to 61.4%, from 74.3 to 45.8% and from 72.7 to 54.5% for live feed, mixed diet and artificial diet, respectively.