i dont know...

Question
is it true that guinea pigs, have to live with another guinea pig to be happy?

Answer
Fabi,

Guinea Pigs prefer to be in groups as they are group animals naturally. But a person can own a single Guinea Pig, but the single Pig will require more attention from the owner so that the pig doesn't get lonely and depressed. So it is better to have more then one Guinea Pig but it isn't like they can't be happy with out a companion as long as they have a lot of attention from the owner. It really depends on how much time the owner can spend, as a single Guinea Pig needs more the 2 hours of attention daily while 2 Guinea Pigs can be fine with 2 to an hour of attention daily.

I hope this helps,
   Take care,
     Jules