I read on the food packaging to feed several times a day. I really don't want to overfeed--how many is "several" and how much at a time? I've just been feeding once a day at night only enough to be entirely gone within 5 minutes--am I starving my fish? Would they do better with more? So far, I think I've been successful because guppies are very forgiving, but I've added a couple other kinds that may be more sensitive, and I want to be sure they thrive. Help, please.