The Wood Stack and Fish Basin are inextricably linked. You need as much wood as you can hold to upgrade your fish and vice-versa. You'll also have to have max Vikings for your Meade Hall level and you always need to upgrade your stack before upgrading your Academy.
The Wood Stack is one of the main resources storage buildings in the game.
The bigger your Wood Stack is the more
you get in Toothless' bags from Special Events.