Yeah, I recall Calfo mentioning that the "gunk" in frozen foods is (quoting him) "rocket fuel for algae", I did use to rinse it fairly well, drain it then flop globules of mysis in the tank. But I've held back on using frozen food for fish food for a while due to cost, however it seems the reduction in feeding from daily to every 2 to 3 days hasn't seem to really put a dent in the algae growth and probably is upsetting my chromis to the point of starvation, the tangs do fine however.