高密度轮虫对点带石斑鱼早期仔鱼培育影响的研究

Effect of rotifer at high density on culturing for early stage larvae of Epinephelus malabaricus

本试验在水体为1000dm3、仔鱼密度为15ind. dm3条件下,研究不同轮虫密度(10、25、40、70、100ind. cm3)对点带石斑鱼早期仔鱼摄食和生长的影响.至仔鱼12日龄的培育试验结果表明,在点带石斑鱼早期仔鱼的培育过程中,投放轮虫对水质有影响,特别是在2～6日龄间,DO值和pH值都有一降低过程,但随后即回升并相对稳定;轮虫密度越高则pH值越低,pH值最低出现在4～6日龄,4日龄时10ind. cm3组的pH值比100ind. cm3组高0.32在10～100ind. cm3的轮虫密度范围内,较低的轮虫密度对仔鱼的生长有利,12日龄10ind. cm3组仔鱼的全长比100ind. cm3组高31.83%,但100ind. cm3组仔鱼的成活率比10ind. cm3组的高出近一倍;不同轮虫密度下仔鱼摄食轮虫数量的差异并不明显;但9日龄以后,过高的轮虫密度100ind. cm3下仔鱼生长速度显著降低.

Five experiments on feeding and growing of the early stage ofE.malabaricus larvae at the content of 15ind./cm^3 in 1 000dm^3 water were respectively conducted at the rotifer densities of 10,25,40,70and 100 ind./cm^3.These experiments rearing larvae to 12 days indicated that (during) the early stage of larval rearing,introduction of rotifers affected water quality, particularly at larval age 2～6days both DO and pH dropped, and then they went up and maintained relatively stable. The higher the rotifer density, the lower the pH value. Overdense rotifers degraded water quality to the extent, which still not exceeded the survival range of larval fish. Within the densities of 10～100 ind./cm^3, the rotifers benefited the growth of larval fish at lower density, and increased the survival rate of larvae at higher density. Meanwhile, at various densities of rotifers, there was no significant difference in the number of rotifers fed by larval fish. Afterage 9 days, the growth of fish larvae slowed down significantly at the rotiferdensity of 100 ind./cm^3.