Bottom Feeder Foods
Generally fish feeding follows a five minute rule. When you have bottom-feeders in your aquarium, they may suffer from this guideline. Bottom-feeders need pellet fish food or sinking wafers designed to sink rapidly to your aquarium floor so that your other fish don't eat it first. Herbivores like plecos should eat sinking algae wafers; carnivorous bottom-feeders commonly eat shrimp in nature as that's what they can get to. (Plecos will also eat untreated driftwood!)
Many bottom-feeders are nocturnal; use bottom-feeder fish food at night, both to encourage eating and to cut down on food consumption by other fish.