BLUE TONGUE SKINKS

All my skinks , even the ones that are separeted from the rest , have diarrhea
But they are all eating well and look healty.
I feed them dogfood with vegetables included , sometimes banana , mango , rosebeetle larvea ( dola's ) , morio worms , waxlarvea's.
En it smells verry hard !
What could cause this?

Fruits, especially banana, and egg tend to cause nasty, runny, smelly poops.

When you say diarrhoea do you mean true diarrhoea where the faeces is in liquid form, or are the faeces soft and partially or fully formed?

If it is true diarrhoea then they will be also dehydrating and losing valuable electrolytes which need urgent replacement. It would be best if a sample could be analysed a soon as possible to determine if a bacterial infection such as an overgrowth of clostridium is the cause.