Callochromis pleurospilus, male. I kept and bred this mouthbrooding species many years ago. The pink edge of the male's anal fin is held in a curve in front of the female during spawning and acts as an 'egg dummy' (instead of the commoner 'egg spot(s)' in males' anal fins) to induce the female to try to pick it up and thus ingest sperm to fertilise the eggs which she picked up previously.
The latest DNA research shows that Callochromis is part of the 'featherfin' group, with such beauties as Cyathophraynx furcifer, while the Xenotilapia species are more distantly related, although they are very similar to Callochromis in appearance and feeding behaviour.