It really depends on what Cichlid. All Cichlids in the wild co-habitat with non-Cichlids. The key is researching what other fish are found with the Cichlids you want to keep. Then there are some fish that are not found in the same environment, but may be compatible. For example, Discus do well with clown loaches, however, clown loaches are not found in the Amazon, but in Asia. So just when you think you have it figured out, it may surprise you.
My best advice is to ask an experienced hobbyist if they think your choices would be compatible. Then it is always wise to keep an eye on them for the first few days to make sure everyone is getting along okay. You don't want to wake up to find that half your fish are gone, or to have dead bodies spread across the bottom of the tank.