+1 depends on a lot. I have a tank of wicked aggressive crystals that have to be fed every day or they will start attacking each other. My Taiwans are fine every other day or every 3 days because they aren't as aggressive. It's dependent to the aggression of the colony, shrimp species, biofilm, etc. My tibees were the same way, wicked aggressive and had to be fed every day and protein twice a week minimum. That's not saying all crystals are like that or all tibees, just my particular colonies.