Tolerance of Juvenile Triploid Rainbow Trout(Oncorhynchus mykiss)to Supersaturated Total Dissolved Gas
To understand the tolerance of triploid rainbow trout(Oncorhynchus mykiss)to supersaturated total dissolved gas(TDG)during early development,two sizes of rainbow trout juveniles with body weights of(0.22±0.13)g and(0.68±0.17)g were placed in a water tank and exposed to supersaturated total dissolved gas(TDG)with saturations of 110％-130％,130％-150％,and 80％-85％(control group)injected into the tank using a self-made total dissolved gas generator.The behavioral changes of behavior,relationship between mortality rate and time at TDG saturation,and the median lethal time(LT50)were investigated in the triploid rainbow trout juveniles exposed to different saturation levels of water.The results showed that the symptoms of gas bubble disease were increased in juvenile triploid rainbow trout under TDG supersaturation stress with the increase in stress time and TDG saturation,with very significant correlation between LT50 and TDG saturation and size(P＜0.001).When the TDG saturation is between 110％and 130％,the LT50 of small and large size fish is 18.48 h and 4.45 h,respectively,indicating that small size fish have high tolerance;when the TDG saturation is between 130％and 150％,the LT50 of large size fish is 1.54 h,indicating higher tolerance.The findings are benefit to evaluate the effects of TDG supersaturation on different fish species,and provide a reference basis for the development of fish protection measures.
total dissolved gas(TDG)supersaturationtriploid rainbow troutgas bubble diseasetolerancemedian lethality time
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