Gameplay Suggestion for certain fishy types.

For fish types like Fizz / Nami / Tahm, a new passive called 'Fish out of Water': You must refill your 'breath bar' via stepping in river (an additional bar) before it reaches 0 or you will take x% of health dmg over time until you drown/die.

Personally I think it is funny. Perhaps drinking a pot or being the target of a water related spell could be other ways in lieu of stepping toes in river to catch ur breath.

edit: could have a beneficial pasive as well: at home in the water; or home field advantage: movement speed (perhaps small attack speed / cdr buff) increased in the river that decays quickly once leaving the river.