Taxonomy & naming
The species was described by the French ichthyologist Jacques Pellegrin in 1913 as Paratilapia maculipinna, in the Bulletin de la Société Zoologique de France (volume 37, dated 1912 but published the following year). The type locality is Lake Victoria (Victoria Nyanza) at Port Florence — the colonial name for Kisumu, in Nyanza Province, Kenya — and the holotype (MNHN 1912-0258) is held at the Muséum national d'Histoire naturelle in Paris, where it was catalogued by Blanc in 1962. Pellegrin's placement in the catch-all genus Paratilapia did not last: P. H. Greenwood, who spent decades revising the Lake Victoria cichlids, transferred the species to Haplochromis in his 1967 revision (Part VI), and that combination was upheld by van Oijen and colleagues in the 1991 CLOFFA checklist. Haplochromis is the great 'wastebasket' genus of the East African lakes, and in his later work Greenwood split many of its Victoria members into smaller segregate genera defined by trophic specialization. Modern usage by most ichthyologists and aquarists keeps these Victoria species under the broad heading Haplochromis pending a stable, lake-wide revision, and that is the convention followed here. The species is monotypic and carries no junior synonyms.
Morphology
Haplochromis maculipinna is a modestly sized haplochromine, reaching about 6.5 in in standard length according to FishBase, which places it among the larger members of the flock rather than the many sub-4 in species. The body is the typical laterally compressed, perch-like haplochromine form. Its diagnostic feature is the one the name records: the specific epithet combines the Latin macula, 'spot', with pinna, 'fin', and refers to two rows of dark spots on the dorsal fin (etymology per the ETYFish Project). As in essentially all Lake Victoria haplochromines, coloration is strongly sex-linked — breeding males develop bright nuptial colours used in courtship and species recognition, while females and non-breeding fish are a more cryptic silvery-brown. Detailed live colour descriptions for this particular species are sparse in the public literature, a reflection of how thinly many flock members are documented; the spotted dorsal and the larger-than-average size are the most reliably reported external characters.
Habitat
The species is endemic to Lake Victoria, the vast, shallow equatorial lake shared by Kenya, Uganda and Tanzania, and is recorded between roughly 1°N and 3°S. FishBase reports it as benthopelagic over a depth range of about 10–30 ft. It inhabits sheltered gulfs and bays where the bottom is soft mud, or sand and shingle; a few specimens have come from exposed beaches and from deeper water (about 34–39 ft) near off-shore islands. Lake Victoria is hard, alkaline equatorial water — typically pH on the order of 7.2 to 9.0 and surface temperatures around 73–81 °F — and the haplochromines of the inshore and sub-littoral zones, including this one, are adapted to that warm, well-buffered environment. Its preference for calm, soft-bottomed embayments rather than open water or rocky reefs is characteristic of a number of the flock's insect-and-fish predators.
Feeding
Haplochromis maculipinna is a predator. FishBase records its diet as fishes and insects, and assigns it a trophic level near 3.9 — squarely in piscivore/insectivore territory, well above the algae- and detritus-grazing members of the flock. The Lake Victoria species flock is famous precisely for this kind of trophic partitioning: closely related haplochromines diverged to exploit nearly every available food resource — algae scrapers, plankton sievers, mollusc crushers, insect pickers, scale eaters, paedophages and fish hunters — and maculipinna sits with the fish- and insect-eating guild. Working the soft-bottomed gulfs and bays it inhabits, it would have taken aquatic insect larvae and small fishes, including the fry and juveniles of other haplochromines. This predatory habit is also relevant to its fate: the fish-eating haplochromines competed directly with, and became prey for, the introduced Nile perch.
Mating
No detailed courtship account has been published for this species specifically, but its reproductive biology follows the well-documented Lake Victoria haplochromine pattern. These are polygynous maternal mouthbrooders with little or no lasting pair bond. Males in breeding condition develop bright nuptial coloration and display to females, and species recognition during this courtship — driven heavily by male colour pattern under the lake's light conditions — is thought to be one of the engines of the flock's rapid speciation. Spawning is brief: the female lays a small clutch, the male fertilizes the eggs, and the female immediately takes them into her mouth. Males do not participate in brood care.
Breeding
Haplochromis maculipinna is a maternal mouthbrooder — FishBase records 'mouthbrooding by female' — as is the entire Lake Victoria haplochromine radiation. After spawning the female incubates the fertilized eggs in her buccal cavity, releasing the free-swimming fry only after they have absorbed the yolk sac, and continuing to shelter them in her mouth when threatened during the first days of free swimming. Clutch sizes for this species are not separately published; Lake Victoria haplochromines of this size typically carry broods on the order of a few dozen large, yolk-rich eggs, the trade of low fecundity for high per-offspring survival that mouthbrooding allows. Parental care is by the female alone; the male contributes nothing after fertilization. No aquarium spawning records specific to maculipinna are available.
In the aquarium
This species is not a hobby fish. Unlike a handful of charismatic Lake Victoria haplochromines that reached the aquarium trade (the 'flameback', 'Christmas fulu' and similar), Haplochromis maculipinna has essentially no presence in the hobby and there are no established husbandry or captive-breeding records for it. Any keeping notes can only be inferred from its biology and from general Victoria-haplochromine practice: it would need hard, alkaline water (pH around 7.5–8.5, moderately hard) at roughly 75–81 °F, a soft sand bottom matching the gulf-and-bay habitat it favours, and — as a 6.5 in predator that eats fish and insects — a large tank, robust filtration, and tankmates too big to be swallowed. Like other haplochromines it would be a polygynous mouthbrooder best kept one male to several females to spread male aggression. But these are extrapolations: the honest position is that the species is unstudied in captivity and effectively unavailable, and serious conservation interest in the Victoria flock now centres on a small number of targeted species rather than on this one.
Conservation
The IUCN Red List assesses Haplochromis maculipinna as Data Deficient (assessed 31 March 2010 by Witte, F. & de Zeeuw, M.P.; published 2010). The assessment notes that there is no information on the species' population size now or in the past, and that its presence has never been confirmed in the Tanzanian sector of the lake — flagging the assessment as needing updating. Eschmeyer's Catalog of Fishes goes further and tags the species as 'extinct', though without population data this should be read as a strong concern rather than a confirmed fact. The backdrop is the catastrophe that overtook the Lake Victoria flock in the late twentieth century: the upsurge of the introduced Nile perch (Lates niloticus), compounded by eutrophication and intensified fishing, drove a collapse in which an estimated 200 or more haplochromine species disappeared or became extremely rare, the sub-littoral and deep-water haplochromines vanishing almost completely (Witte et al.; Barel et al.). As a fish-eating, gulf-and-bay haplochromine, maculipinna belonged to exactly the guild most exposed to that predator. Whether any population survives is genuinely unknown — hence Data Deficient — which is itself a measure of how little of this extraordinary flock has been monitored since the collapse.