Fish only growing to the size of the tank is a horrible misconception. And you should be feeding a lot more than nori and some pellets. I'm kind of a freak about feeding my fish. I feed plankton, krill, spirulina enriched brine, nori, formula one, formula 2, pigmy angel formula and spectrum on a rotation. The spectrum is basically a snack if I am pressed for time. I also add marine C, zoe marine and selcon to all the food except nori and spectrum. Occasionally I use garlic extreme as well. Mostly, just for new fish in my Qt.