بررسي رشد و بقاء لاروماهي سفيد با تغذيه روتيفر و مقايسه آن با غذاي كنسانتره

The role of rotifer(Brachionus plicatilis) in increasing survival of Rutilus frisii kutum larvae and it’s comparison by concentrated food

Kutum (Rutilus frisii kutum)is one of the most important and economical fish of the south shores of the caspian sea. Each year millions of artificially propagated larvaes of this fish are released to the caspian sea for retoration purpose. in this research we studied the role of rotifers being fed to larvaes and their effect on survival, in comparison with larvaes which were fed by concenterated food on a common method in hatcheries. The experiments at first were accomplished in two treatments (rotifer feeding and concentrated feeding) and each one had three repetitions (each repeatitions by 1100 pieces larvae which weighted 5 mg). the result proved that %27.5 of the larvaes fed by concentrated food died after 26 days and %46.6 of them died after 40 days. the rate of loss in the group which were fed by rotifer incomparison with the first group (larvaes fed by concentrated food) was ignorable , so that the rate of loss stood at %6.6 in 30 daysand %7 within 40 days. it means we had %0.4 loss in 10 days. The average of larvaes weight and length was estimated respectively 140 mg and 24.5 mm (in group by rotifer feeding) and 26 mg and 12.5 mm (in group by concentrated feeding) after 26 days. Although the results showed that in natural pools of Rasht (animal husbandary) the average of larvaes weight and length was 180 mg and 27mm.The final achievment showed that within 40 days the average weight and lenght of larvaes fed by rotifer stood as 440 mg and 31.36 mm and those fed by concentrated food as 17.2 mg and14.75 mm . These findings in comparison with weight and length of larvaes in pools (342.8 mg and 31mm ) showed that generally feeding by rotifer is more effective in larvaes growth. it is worth to consider that the fish larvaes fed by rotifer survived noticeably more than the fish larvaes fed by concentrated food.