Yes, I ment that I had heard of plecos attacking other small aquatic creatures.
My pleco was not hungry, had been feeding daily on sinking algae pellets. I don't know exactly why it was attacking the frog... it seemed to be a territory issue, however, even though the frog was peaceful and never bothered the pleco.
what kind of pleco was yours? some are more omnivorous than others. it may have been wanting protein that the algae wafers were not providing. all of my plecos get a varied diet of wafers, sinking carnivore pellets, krill, bloodworms, regular shrimp, zuke, cucumber and various other veggies, and home made loach food