If you are introducing a new rabbit to your colony, it is necessary that it happens on neutral ground. If you introduce a new rabbit to an existing rabbit's home they are bound to start a fight. A good way to introduce the rabbits is to take your rabbit with you to the breeders/pet shop and let them get to know one another there. If they get along well you can take them home in the same travel box. This also helps with bonding as both of them will be a little nervous in the car.
When you get home, again place them on neutral territory and allow them to check each other out. Supervise them at all times when they are getting to know each other and assess if they are getting along ok. If they seem to have fallen in love with one another straight away, you can place them in the same cage that night. If the two are still a little unsure it is best to give it some more time. When you finally put them both in the same cage, make sure there are 2 water bowls and 2 feeding bowls etc. They might not yet be ready to share.
Rabbits are sociable, but they still need time to settle in with their fellow bunnies.
In most cases it will take a few introductory sessions before the two will be happy with each other's presence. Make sure you have a spare run for the new rabbit to live in before it’s time to move. House the rabbits within sight of each other and place some of the other rabbit’s droppings in the run each day so that they get used to their companion’s scent. Let them socialise on neutral territory every day until you are sure that they are getting along. Once the two are happy with each other and show no signs of fear or aggression, you can house them together.
Again, if you are keeping males and females together be sure to neuter at least one of them or you’ll soon have a much larger number of rabbits living in your house. Breeding should only be done by those who know what they’re doing.