Hi Silver. You will find that the kribensis, or rainbow cichlid, or to be more exact, pelvichromis pulcher, has been written about extensively on the internet. I became interested in them because I wanted a cichlid but could not have a big cichlid tank, and they are smaller and generally more peaceful than the average cichlid. That said, they are still a territorial fish, definitely not a pushover, and they love
their caves.
I think my krib is my most beautiful, most interesting fish. As soon as I had him, I knew I would buy a bigger tank for him (he was in a ten gallon). I want to find a female and I hope that they will raise some fry. But I regress: your question was regarding kribs in a community tank. I would not dream of putting a krib pair in my community tank to breed. I have, however, added my krib to my 28 gallon tank, and he is doing very well there. You can see him and the tank I have added him to at this thread:
My Photos
As always, a lot depends on the temperment of the individual. My fish is territorial, but so far I have not seen any unbridled aggression. None of the other fish appear to be afraid of him. Again, he is not breeding, and I think that is important, especially since I have bottom dwellers.
So when you see that kribs are "community fish", and you will see that all over the place, I would keep in mind that he needs his cave, he needs space at the lower level of the tank because he'll generally stay there, and it might be best not to get him a mate. That's my two cents. Hope it helps.