七鳃鳗，八目鳗一种七鳃鳗科的原始细长淡水或溯河产卵鱼，特点是长有无。
Any of various primitive elongated freshwater or anadromous fishes of the family Petromyzontidae, characteristically having a jawless sucking mouth with rasping teeth.
被捕获的鱼的平均重量也在减小，这正是研究机构大为担忧的，尽管产卵鱼的总存量从1985年以来已略微增加。
The mean weight of fish caught is also dropping, which worries the research institute greatly, though the biomass of spawning stock has increased slightly since 1985.
这种鱼一次产卵数千个。
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