Water quality and survival rate of Rhamdia quelen fry subjected to simulated transportation at different stock densities and temperatures

ABSTRACT. Transportation of live fish is routinely done in aquaculture; therefore, the aim of this study was to analyze the water quality and survival rate of Rhamdia quelen fry (2.55±0.44 g) following 4, 8 and 12h of simulated transportation, at stock densities of 30 and 60 fry 5 L-1 and temperatures 15, 20 and 25oC. Dissolved oxygen, pH, electrical conductivity, total ammonia, nitrite, nitrate, turbidity, total alkalinity and survival were analyzed. Temperature and time had a significant influence on ammonia, pH, electrical conductivity, and dissolved oxygen levels, and fish died after 12 hours of transportation simulation when kept at 20 and 25ºC. The density directly affected the water quality parameters, such as the increase in electrical conductivity and turbidity, and decrease in dissolved oxygen and pH at the density of 60 fish 5 L-1. In conclusion, the transportation of R. quelen fry should be carried out at temperatures between 15 and 25°C, for periods of less than 12 hours, and at stock density of up to 6 fish per liter of water so as not to impair the homeostasis of the fry, and consequently, their survival.

摘要：水产养殖中活鱼运输为常规作业环节，本研究以体重为2.55±0.44 g的奎伦鲶（Rhamdia quelen）鱼苗为研究对象，设置每5升水体30尾、60尾的放养密度，以及15℃、20℃、25℃的水温条件，开展4、8、12小时的模拟运输实验，旨在分析该过程中的水质变化与鱼苗存活率。本研究检测的指标涵盖溶解氧、pH值、电导率、总氨氮、亚硝酸盐、硝酸盐、浊度、总碱度以及鱼苗存活率。结果表明，水温与运输时长对总氨氮、pH值、电导率及溶解氧水平存在显著影响；在20℃与25℃环境下，经12小时模拟运输后鱼苗全部死亡。放养密度直接影响水质参数：当放养密度为每5升水体60尾鱼苗时，水体电导率与浊度升高，溶解氧及pH值显著下降。综上，奎伦鲶鱼苗的运输作业应在15~25℃水温下进行，运输时长需控制在12小时以内，且放养密度不超过每升水体6尾，以此避免破坏鱼苗体内稳态，保障其存活率。