UDC (639. 311)
N. Grudko, teaching assistant
I. Sherman, Doctor of Agrarian Science, professor
Kherson State Agrarian University
Special research attempting to investigate correlation between duration of cultivating paddlefish hatchlings and main fishery markers (survival rate, average mass, fish production) and biochemical composition .
The cultivation of paddlefish hatchlings were placed in plastic tanks for 20, 25 or 30 days.
Stock density was 750 fishes/m2 in all variances. Stocking was provided using gauge method. Experimental material was selected using the analogue groups method with average individual bodymass (AIB) as 10,4 ± 0,5mg. The Fish were fed zooplankton (mainly Daphnia sp. ) 5 times a day.
The average water temperature in tanks for 20 days was about 19. 6o. The water temperature was higher in variances of 25 and 30 days long – 20,2oC and 20,8oC respectively. The chemical parameters of the water did not exceed normal values. Common water mineralization was up to 575. 3 mg/l.
We established that the elongation of the growing process from 20 to 30 days increased average mass from 0. 51g to 1. 73g therefore increasing fish production from 235g/m2 to 718g/m2. Paddlefish hatchlings demonstrated the most significant growth happened immediately after changing feeding from endogenous to exogenous type. Maximal values were registered in last 5 days of cultivation and reached 38. 7-55. 9%.
The longer the cultivation period of hatclings the better the body composition. Water decreased from 79. 35% to 78. 80%, protein increased from 18. 60% to 18. 67%, fat increased from 1. 88% to 1. 89%. Received data shows that elongation of hatchling growth improves then main fishery markers and biochemical composition of paddlefish. Despite of higher operational cost of such procedures we receive higher quality of fishstock which can benefit us later on.
Key words: ongrowing duration, fish production, biochemical composition, paddlefish hatchlings.