Some collareds do not eat every day. There are people who feed them every other day or every 2 days if that's when they are are hungry. So if your guys keep a good weight and are content and do not want to eat everyday than it is normal for them.

I personally have always offered food every day, most do eat, but there are times one will not seem interested that day. I happen to think when you have quite a few/ or many they dive after the bugs .. to make sure they get their fair share

But as I say, if you notice yours looking thinner/ losing weight after a time, than begin to look into temps, parasites, so on...
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PHEve / Eve