cheerios are a good source too, i heard you can even use tropical fish food, but I don't know about that one for sure. I just keep mine in a cricket food substrate. its not too bad when it comes to sifting them out. They wont eat when in the fridge. Not sure about the gut load staying. I usually just warm mine up every couple days or so to let them eat. The potato slices are more for moisture I think, i dont think it would hurt to throw one in when they are warmed up to eat.

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2.1 chocolate labs and bassett (Harley, Barker and Capone)
1.0 leopard gecko (Nacho)