Abstract: Field exposure experiment was carried out to explore the tolerance and avoidance characteristics of Myxocyprinus asiaticus (Chinese high fin banded shark) to TDG supersaturated water under different water depths during flood discharge. The mortality of Myxocyprinus asiaticus was 42.5%, 30%, 17.5%, and 15% respectively when water depth was 0~0.3, 0.3~1.3, 1.3~2.3, and 0~2.3 m in natural river course downstream of dam with a TDG of 115%~117%. A low TDG level could also lead to the death of juvenile Myxocyprinus asiaticus. Nevertheless, increased water depth notably reduced the mortality of the juveniles, indicating that the depth compensation could effectively alleviate the damage of TDG-supersaturated water to juvenile Myxocyprinus asiaticus. In addition, juvenile Myxocyprinus asiaticus boasts an ability of avoiding the damage cause by supersaturated TDG with the help of water depth compensation while adult Myxocyprinus asiaticus has no obvious such behaviors. The research results offer a reference for the formulation of protection measures on fish.

Key words: Myxocyprinus asiaticus, supersaturated TDG, flood discharge from dam, water layer, field exposure experiment, tolerance, avoidance