Also known as the mandarin orange or mandarines, mandarins are the fruit of a small citrus tree of the same name. They look like other types of oranges and usually eaten raw or in fruit salads.
So can guinea pigs eat mandarins, and if they can how much of them can be eaten?
Lets take a look at their nutritional data and find out more about them.

In particular, their acidic, fat, calcium, sugar, and phosphorus content is of most interest as far as piggies are concerned.

Read more at http://www.healthaliciousness.com/nutritionfacts/nutrition-comparison.php?o=9218&t=&h=&s=76.00&e=&r=#pWbBekOtG1TcwAl8.99
As you can see, mandarins contain a hint of phosphorus and calcium, they are also a little acidic, and a quite sweet. They also contain a hint of fat and calcium.
They also contain a nice amount of vitamin c as well.
So guinea pigs can eat mandarins but only once or twice a week because of their acidic and sugar content.
They can only be eaten fresh and raw though, don’t feed them tinned mandarins.
Can guinea pigs eat mandarin peel?
However, mandarin peel or skin can be eaten by guinea pigs. In fact it has similar amounts of vitamin c as the fruit itself