What fish can be used for 'minced fish' in Chinese cooking?
I use a combination of Basa and what the shops mark as Spanish Mackerel (the basa usually being frozen in Australia) ... When fresh is available, I like to use Ling fillets.

I have had varied success with whiting fillets... Frozen whiting can sometimes have no flavor whatsoever.

Someone else suggested monkfish and butterfish.

Tuna made for an interesting meatball, and I used that with a Tom Yum preparation.

Addition of shell fish such as prawns also make a nice variation.