Question

There is ( )fish in the fridge.

Answer 1

There is (some) fish in the fridge.
用some的话，这里的fish指的是鱼肉。
There is (a) fish in the fridge.
用a的话，这里的fish指的是（一条）鱼

Answer 2

There is no fish in the fridge.
There is some fish in the fridge.