If I were a fish I would be a male Angler fish.
Why specifically a male one you might ask. Well, the answer is in their life cycle. Once we get "big enough", and the big is not very big mind you. Not compared to the ladies. Once we are big enough all we really would think about is finding a nice big lady to bite onto.
Wait, what, bite on to? Yes, bite on to. And then slowly over time merge our bodies with hers leaving only the gonads as my last remaining identifiable part, or balls for you french people out there. The rest of me would then be joined forever into here. Along for the ride, not ginging any more car in the world. My mission now complete with providing the lady with "sauce" and minimizing my effort as well while maximizing the enjoyment. No matter how rarely one would be used, basically only being gonads would ensure ecstasy levels of enjoyment. At least that is the theory.
And for bonus cool, being merged like this also creates a very real chimera. Which is like insane levels of cool all on its own.