When I was a kid my best friend's Dad was a Christian preacher, and they had a big tank of guppies in their living room. My friend's little sister once asked me if my guppies were also married. I felt bad because mine weren't, but I couldn't sort out who was with whom, and forgot about it til this thread.
At this point, I've watched the shenanigans of ovophile and larvophile mouthbrooders, switch mouthbrooders, open spawners, cave spawners, peat divers, plant spawners, egg scatterers, hermaphrodite self cloners, livebearers, egg carriers... I've seen females with several males, males with several females, pairs bonded for life, pairs bonded for lunchtime, all possibilities.
I've never kept
@CaptainBarnicles pet gorillas (they can't swim) but I have gone to some large aquarium conventions full of creatures who seemed to be courting in random patterns.
I've always liked seeing my fish breed, because I've always liked the results. I like raising baby fish and watching them develop. The ways fish go about making that happen are just part of life's rich pageant.