I had to do that with Neptune and one of my cories. Neptune would always sneak up on one particular cory (the smallest of course) and then nip at him. He would always do this when he thought I wasn't looking though. Such a trouble maker LoL!
King PK Wasabi; HMPK Frostini; 5 CT Bettas Jewel, Shimmer, Opal, Scarlette (aka Ms. Piggy), Pixie; 1 SD Neptune; 1 HM Gypsy; 1 DTHM Pebbles; 4 Orange Von Rio Flame Tetras, 5 Bleeding Heart Tetras, 4 Harlequin Rasboras, 2 False Julii Corydoras Salt & Pepper, 1 Bristlenose Plecostomus Hoover, 2 Pictus Catfish, 1 Albino Rainbow Shark, 5 Dension Barbs