Originally Posted by RWaters
That fish looks like a pale Melanochromis auratus, an aggressive cichlid from Lake Malawi. The females are yellow.
This would be my quess as well. Is that a hap moori in the back? comparing the two sizes is not exact in a picture but the sizes of the two would make me think the front one is too large for a krib. I might guess that the fish was purchased out of the "assorted cichlids" tank at a shop. That is where melanachromis are often found. They often make a very nice looking fish when young as they have very bright horizontal stripes in yellow and black. But they also become absolute killers when mature. They are one cichlid, I will never own again.