I also feed frozen plankton but they do not seem to enjoy this as much as some of the other foods I give them, but they still eat it. I give it to them when I get home. I have a varied feeding regimen that has resulted in great growth. my GT has grown from 1.5" to about 4" in two months. I feed three times a day, morning he gets color flakes, after noon I alternate between sinking cichlid pellets, frozen brine shrimp, frozen bloodworms, and frozen plankton. Evenings I give shrimp pellets and algae wafers. I feed whole night crawlers as snacks 3 to 4 times a week. He really loves the earthworms and normally wont even let them hit the gravel before he takes his first nip at them. I would say overall the best way to give your cichlid the best coloration is to give them stable water conditions and feed them a varied diet with vegatables as well.