Board Thread:Game Help/@comment-33560829-20171104071945/@comment-34524365-20180205040012

you can only catch one spesific quest fish each day, and it is the fish that the angler asked you to catch that day also note that you can still catch a quest fish even before meeting the angler, if the fish you are supposed to catch is that fish (e.g. if you get dirt fish when you go fishing, that means today's quest is to catch the dirtfish thus you can give it to the angler when you find him later before the next day begins / before 4:30 AM) so if the angler ask you to catch the clown fish (ocean) you can't fish in the forest and hope to catch, say, a bunny fish

if you are fishing for the correct fish quest that was up, you should be able to catch it if you keep fishing (I think the quest fish catch rate is the same as the uncommon items/fish) although I think there are some quest fish that are maybe time-related, like I never actually catch a zombiefish in the morning, but I can easily get it at night (I can't confirm this though) it may or may not be true