At 4-5", a few feeders can do the trick.
My most recent tigrinus was trained over to pellets in a matter of days by feeding zebra danios. The danios were fed sinking carnivore pellets. I would drop them near the tigrinus, and when the danios got close, he would eat the danios. However, they're a fairly fast little fish, and the tigrinus missed a few times. It was blind luck that it happened to inhale a pellet, but after that, pellets meant food, and it has been zero effort since. I feed every other day to my tigrinus/zebra pleco tank.