Fish die more times per year due to over feeding. I'm sure it maintains a balance as long as there's no obvious sigs of starving and you still offer the essentials, fish only process 50% of what they eat, so if the pleco eats crap all day he is getting 50% food 50% poop, in which, he will only process 50% of making 25% nutrients consumed. Not exact but a good idea of whats going on, so basically you offer your pleco half of what the other fish consume, but there's more fish then plecos.
My crayfish and ghost shrimps live on whatever I feed my Piranha, but I feed variety, therefore they get pellets, talapia, shrimp etc so no mater what they get enough nutrients, you should still offer a sinking pellet or veggies as treats.
Go S. Vettel #1 rb8