Though mine are young (all three 1-1.5"), they are all slim and very active swimmers. Hmm. I might watch him closely during feedings, see if there is a way that you can keep him at bay while the others eat. After all, if he fattens up on pellets, he isn't likely to do his algae eating duties. Imagine big macs and ice cream cones falling from the sky vs. harvesting your own vegetables to eat. Which would you choose?