That is a Labidochromis caeruleus "Lions Cove Yellow" They are pretty hard to sex by eye, but generally speaking males have black in the anal fin. However, occassionally females will have this too. This fish is from Lake Malawi, and is endemic to that lake. They are maternal mouthbooders, they usually breed harem style, one male to many females, no pair bonding, and there is no parental care. They hold the eggs/fry in their mouths for 21 - 28 days, and usually spit in the rocks.
Hope that helps!