When new rats are introduced into an existing rat group, a proper introduction process should be followed. If the process is not followed, or steps in the process skipped, there is a chance that the introductions will not be successful.
For the proper introduction process, please visit these sites:
It is very important that rats have the company of their own kind. Only when all avenues have been exhausted, should a rat live on it's own. Neutering male rats can help with integration.
