My best guess is Snailfish

Well, actually, that should be the final fish.

The 3rd one seems to be the Tiny Tatsunoko minion.

At least, if I read Cat Became Hungry correctly (It seems like it does have them ordered, it just mixes regular and spear fishing. Looking through all the spearfishing fish, including ones on your image, they all are on there in order. Thus, the fish after Mosasaur is Tiny Tatsunoko and the fish after Ichimonji is Snailfish)