I'd loose the domino. I've heard alot of stories about them,and none are good. As for the others,you'll be surprised how fast they will heal.But in addition to thier wounds,if they are conatantly being harassed by the domino,the stress will do them in. Watch for red streaks in their fins.This will be an infection,treat with antibiotics. And signs of fungus,Fuzzy white spots.GOOD LUCK Think about LOOSING THE DOMINO............STEVE