I have 3 tilapias (used to have 4, it killed itself, it ran into the wall, don't know why this particular tilapia like to smash into things), i know they are teritorial and do eat dead fish but this is my first time seeing them killing and eating a fish, it was a baby koi fish. I used to grow koi and goldfish together with the tilapias but never seen them killing and eating a fish before. Is it a normal behaviour or something else, when they get bigger will their behaviour become worse and eat all the other smaller fish?