I buy seaweed strips for mine and use a tank safe clip to attach it to the side. I do this about 3 times a week to supplement his diet. He eats little bits of it when he wants and the other fish seem to enjoy a nibble of it also. When a snail climbs up and finds it, its funny they think they won the food lottery
You can also soak the strips in nutrients brought from the LFS which help even more.
The seaweed strips i use are a little longer 2x4, but as long as the fish are finishing the ones you are using and not just sitting there causing extra unwanted waste, I would say that's ok and not over feeding.