There has been some ideas about new fish with crustaceans in the names and also about fishing in the deep waters. Adding an actual underwater seascape with lobster, shrimp, crabs etc in the fish names hidden within the water floor would be fun! They would be hidden and couldn't be found with any current spells. Also it would be cool if they looked like the crustaceans in the water but became a" lobster fish" etc once they are caught.
Some new spells to add to this idea are:
The schools for the fish revealed only on the bottom A shrimper spell to reveal where the fish are hidden