Don’t just stick him in the enclosure. There will be a fight. If you are getting your new rabbit from a rescue, ask them to handle the introductions. They will choose a rabbit which will bond with yours. They can meet up in the rescue and you can finally take them home together.
If you are going to do the introductions yourself, you must introduce them on neutral territory - a new pen, the kitchen floor or the bathroom, the back of a van, or perhaps a room in a friend’s house. There must be enough room for them to get away from each other.
Scuffles, mounting and chasing are normal in the beginning. Let them get on with it as long as there isn’t severe aggression like biting or wounding.
If there is severe aggression separate them if necessary by spraying them with water from a water pistol or making a loud noise. It could be that the individuals are incompatible.
A slower way of doing an introduction is to let them smell each other for a few days through a partition first: ie rig up a baby gate or something similar to divide them from each other. Mix their scents by taking bedding from one of them and putting it into the other’s area. Then after a couple of weeks introduce them on neutral ground. Introductions make take time but will be worth it since they will never be lonely again.

SHOULD A RABBIT LIVE WITH A GUINEA PIG?

Guinea pigs are so much smaller than rabbits than they can be severely harassed or even seriously wounded if a rabbit kicks them. Neuter and spay your rabbits, then you can give your bunny a rabbit friend who speaks the same language.

WHAT SIZE HUTCH DOES A RABBIT NEED?

Think BIG when buying your rabbit’s home. A rabbit needs a sleeping compartment, and an eating area. As well as this, there should be an exercise run. The bigger the breed, the bigger the house. Giant breeds need giant houses. Wendy houses, garden sheds, aviaries, summer houses, dog kennels with runs, or even chicken houses offer more room than the traditional hutch. Starter hutches sold in pet shops are ALWAYS too small so are most of the hutches on sale. Buy the biggest in stock or better still order an even bigger one. Minimum size hutch per average rabbit is 5 foot by 2 foot by 2 foot. Double this for two rabbits. Consider a penthouse from http://www.pethouse-uk.com or the largest ark from www.forshamcottagearks.com (remembering that a rabbit can’t reach the outside of an ark), a villa house from www.sprcentre.co.uk or even a dog kennel from www.derbyhouse.co.uk Choose the largest of these houses, not the medium or smallest.

DOES A HOUSE RABBIT NEED A HUTCH?

No. An indoor house rabbit needs a secure den where he can retreat for privacy and sleep. This must be lockable, so that the rabbit can be locked in at times for his own safety. Depending on the size of your rabbit, a crate sold for dogs might be the ideal. This must be big enough to contain a sleeping box, food bowl, hayrack, water bowl and litter tray. Crates are useful for taking in the car or on visits. There are some UK ones on www.shawspets.co.uk or www.croftonline.co.uk Plastic dog beds turned upside down make nice bunny retreats in rooms away from the bunny’s den.

WHAT SHOULD I PUT ON THE FLOOR OF THE HUTCH?

A deep layer of soft barley straw is the warmest most comfortable bedding for an outside hutch. Beneath this, you can put wooden shavings particularly in the latrine area (if you are not going to litter train your rabbit) or special rabbit litter. Indoor house rabbits don’t need such a large amount of straw and some people just put a fleece in their sleeping area.