Taxonomy & naming
Otopharynx tetraspilus (Trewavas, 1935) was described as Haplochromis tetraspilus in the Annals and Magazine of Natural History, series 10, volume 16 (no. 91), pages 87 and 103. The Catalog of Fishes gives the type locality as the eastern shore of the South East Arm between the Bay and Fort Maguire, Lake Malawi. The lectotype is BMNH 1935.6.14.1609, selected by Eccles & Trewavas in 1989, who also placed the species in Otopharynx. Rick Borstein (GCCA, 2004) gives the hobby name Mloto Yellow Princess and shows a male as "yellow fin mloto". The atlas also has a separate page for Otopharynx sp. "Tetraspilus Molariform", which is a different, undescribed form.
Morphology
Rick Borstein (GCCA, 2004) describes males with blue heads, blue-gray bodies and, depending on mood, a yellow underbelly. The dorsal fin has a white-blue blaze, and the anal fin has prominent egg spots. Females have a tan-golden brown base with numerous markings. He reports that males reach 6–7 in and females are about one-third smaller. FishBase gives a maximum of 6 in total length for males or unsexed fish.
Habitat
FishBase lists the species from the southern part of Lake Malawi, and also from the Kamuzu Barrage at Liwonde and the upper Shire River. It lives in vegetated shallow water in sheltered bays, and Rick Borstein (GCCA, 2004) adds that the bottom there is usually sandy. FishBase lists it as freshwater and demersal. The GCCA page gives lake water as hard, with pH 7.4 to 8.4 and 7 to 30 dH; FishBase gives the same pH and dH range for its aquarium fields, with 73–99 °F.
Feeding
FishBase says the species feeds on algae and small crustaceans. Rick Borstein (GCCA, 2004) cites wild stomach contents of algae, bits of vegetation and various small crustaceans. In the aquarium he fed spirulina flake, cichlid flake, New Life Spectrum, Aquarian Tropical Flakes and a home-made paste food.
Mating
Rick Borstein (GCCA, 2004) did not see spawning, but reports that the female excavates a small depression in the sand and releases her eggs, then picks them up in her mouth. The male presents his egg dummies, the female bites at them, and he releases sperm. Before breeding, females plump up considerably and males darken until the sides are almost completely gray. Males leave females alone until the females are ready to breed.
Breeding
Otopharynx tetraspilus is a maternal mouthbrooder. Rick Borstein (GCCA, 2004) kept a group of one male and three females; the male courted and bred with two of them. He finds that Otopharynx spawn only every two to three months, unlike most mbuna. Females are excellent holders. He let one hold for 12 to 13 days and then stripped 35 fry with just a trace of yolk sac. They took Cyclop-eeze and baby brine shrimp at once and grew fairly quickly, but showed little colour until nearly adult. His son Sam Borstein first bred the species and entered it in the GCCA Breeders Award Program.
In the aquarium
Rick Borstein (GCCA, 2004) calls the fish easy to keep and not very aggressive. He kept it in 55 US gal and 90 US gal tanks that were both crowded, and with several more aggressive mbuna. It stayed in the middle to upper tank and avoided conflict, yet kept breeding. He advises a tank at least 4 ft long. Males chase females but he never saw damage. He found it in pet stores only occasionally, with juveniles about $12.
Conservation
The IUCN Red List assessed Otopharynx tetraspilus as Least Concern on 20 June 2018, per FishBase.