Especially as they get older. Love the odd prawn or carnivore pellet but don't over do it as too much meat protein is not good for them. Once or twice a week is plenty for a meaty treat.
Hi, I have a 4 year old Common who is 15". I agree with indigoj. They also need some veggies, mine especially likes mushroom. so he has that once a week. I also feed shelled, frozen peas to all my fish once a week to help prevent bloat (they have never had bloat).