Can Guinea Pigs Eat Bananas?
Guinea pigs can eat banana but in very small amounts and only as a very occasional treat as it has around 12% sugar content and can encourage obesity in your pet.
Too much banana (or any other fruit) can cause an upset stomach, so to avoid a poorly guinea pig you should stick mainly to a vegetable based diet with only the occasional fruit treat.
Can Guinea Pigs Eat Banana Skin / Peel
There is very little written about whether guinea pigs can eat banana skin. However, although in the western world we tend to peel our bananas and discard the skin, there are many countries where they do eat it. This probably means that if you're giving your guinea pig a small piece of banana, it is fine to slice it with the skin on and give the fruit and skin to your pet. The skin isn't poisonous.
If you do decide to feed your piggies the banana peel, make sure you wash the skin extremely carefully as banana crops are sprayed with pesticides that will make your pets ill if ingested.