What we did was get two Midwest cages, they have open tops and a tarp on the bottom. We put hay baskets attached to the top part of the cage so they would have to stretch to get the hay. We fed them mostly carrots, we stopped giving them pellets after they were three except to treat them occasionally. We bought our first guinea pig from petco and we adopted from craigslist what we were told was a boy. It was a girl and she got pregnant and had three. She unfortunately died shortly after giving birth. One of her daughters got pregnant from our original guinea pig and we got three more. The original guinea pig was 6 when we had to give him away. He was totally healthy and not very fat at all. Hope this helps! We love guinea pigs and as soon as we get a house we are probably going to get more!