Taxonomy & naming
Haplochromis chilotes was described by the Belgian-British ichthyologist George Albert Boulenger in 1911, in his report on a third collection of fishes made by E. Bayon in Uganda in 1909–1910, published in the Annali del Museo Civico di Storia Naturale di Genova. The species belongs to the enormous haplochromine cichlid radiation of Lake Victoria and its satellite waters — the Lake Victoria region superflock (LVRS), an assemblage of roughly 700 species that arose, in part following an ancient hybridization event, within only the last 100,000–200,000 years. In Greenwood's (1980) generic reclassification of that radiation, chilotes was placed in 'Paralabidochromis' Greenwood, 1956, a group diagnosed by short oral jaws, deep lower jaws, and relatively few stout, straight, unicuspid outer teeth set procumbently at the front of the jaw; it is the type-grouping for the lobe-lipped 'Paralabidochromis' chilotes complex, and aquarists and authors such as Seehausen and Borstein commonly list the fish as Paralabidochromis chilotes. We retain the original Haplochromis heading here because Greenwood's genera are widely regarded as a morphological framework rather than settled, nomenclaturally stable taxa: several of them are now known to be paraphyletic, and many workers (Hoogerhoud 1984, Snoeks 1994, van Oijen 1996, de Zeeuw et al. 2010) continue to refer all superflock species to Haplochromis Hilgendorf, 1888 pending a resolved phylogeny. The species is one of only three formally described lobe-lipped Haplochromis — alongside Haplochromis paucidens Regan, 1921 from Lake Kivu and Haplochromis labiatus Trewavas, 1933 from the Lake Edward system — each a separate evolution of the same striking phenotype. Greenwood (1959) noted that Haplochromis chilotes itself is variable, recognising two sympatric morphotypes in Lake Victoria: one with strongly lobed, medially enlarged lips, a more acute snout and a longer lower jaw, and another with less-developed lips lacking the enlarged medial part. Seehausen (1996) suggested these two forms might eventually prove to be distinct species.
Morphology
Haplochromis chilotes is a moderately sized haplochromine, reaching about 6 in in standard length according to FishBase; in the hobby, males are usually quoted at around 4.5–5 in and females smaller. The body is the typical elongate-to-moderately-deep haplochromine shape, but the fish is unmistakable for its lips: in healthy adults the upper and lower lips are hypertrophied into greatly enlarged, soft, spongy lobes, the species' defining feature and the source of the epithet (from the Greek for "lip-like"). The head is comparatively shallow with a pointed snout, a profile shared with the crevice-feeding insectivores of the rocky shore. Colour is strongly sex- and mood-dependent: females and non-breeding fish are drab and silvery, marked by the "chessboard" melanin pattern characteristic of one of the two main rock-cichlid pattern groups — a mid-lateral and a dorsal-lateral band crossing several vertical bars to give a checkered look, most visible in juveniles and females. Sexually active males develop striking breeding colours and may lose the longitudinal bands while keeping the vertical bars. Sexual dimorphism is pronounced: males grow larger and far more colourful, while females remain comparatively plain and silver. The lobed lips themselves are partly plastic — they are already present in small juveniles but enlarge with repeated contact against hard rock and tend to shrink under unnatural, soft-substrate conditions such as captivity, which is why aquarium specimens often show less dramatic lips than wild fish. Fighting and feeding both wear the lips down, and damaged or torn lips are commonly seen on dominant males.
Habitat
The species is endemic to Lake Victoria, the great equatorial lake shared by Tanzania, Uganda and Kenya and the centre of the Lake Victoria Basin freshwater ecoregion. Within the lake it is a rock-dweller — one of the "Mbipi", the community of cichlids tied to rocky shores and islands. It occupies sheltered littoral and sublittoral zones over hard substrate; FishBase records it from the surface down to about 56 ft depth, with few specimens ever taken over mud. Like most rocky-shore Victorian cichlids it has very specific habitat demands: although Haplochromis chilotes is one of the comparatively few Mbipi sometimes caught over sand, it is hardly ever found more than about 164 ft from rock. Rocky shore makes up only a small fraction (on the order of 10%) of Lake Victoria's largely sandy and reedy shoreline, so suitable habitat is patchy and island-like. The lake's surface waters are warm and hard-water alkaline; haplochromines of the rocky littoral live in conditions broadly around pH 7.2–9.0 and roughly 73–81 °F at the surface, though FishBase's preferred-temperature figure for the species (about 64–75 °F) reflects the cooler deeper water it can also use. Lake Victoria is naturally turbid and has become markedly more so with eutrophication, which has degraded the clear-water visual environment these visually-signalling cichlids depend on.
Feeding
Haplochromis chilotes is a specialised insectivore, and its lobed lips are a feeding adaptation rather than ornament. With a shallow head and pointed snout it works the undersides and crevices of rocks, pressing its fleshy lips against the stone to suck out prey. FishBase reports that it feeds mainly on the larvae of the burrowing mayfly Povilla adusta, together with caddisfly (Trichoptera) and true-fly (Diptera) larvae; Seehausen observed it taking the very mobile larvae of mayflies (Ephemeroptera, Baetidae) that cling to the undersides of rocks, and digging through sand among the rocks with its over-sized lips. Its trophic level is estimated near 3.2. The functional value of the lobed lips has been debated across the thick-lipped cichlids that have evolved convergently in Lakes Victoria, Edward, Tanganyika and Malawi: proposed benefits include improved prey detection through a larger olfactory surface, cushioning against impacts when the fish bumps rock while feeding, and forming a seal against the substrate to boost suction when sucking insects out of interstices. Within the rocky-shore community Haplochromis chilotes partitions the insect resource from its neighbours by morphology — its shallow head and pointed snout suit reaching into crevices, in contrast to steep-headed rock-surface grazers that take prey off open rock faces.
Mating
Like the rest of the Lake Victoria flock, Haplochromis chilotes is a polygynous, sexually dimorphic mouthbrooder in which males do the displaying and females do all the parental care. Males establish and defend territories among the rocks and develop intense breeding colours to court passing females; rival males fight, and the lobed lips of dominant males are frequently torn or scarred in these contests. There is no lasting pair bond — a receptive female visits a displaying male only long enough to spawn, after which she leaves to brood alone. As in other haplochromines, courtship is brief and ritualised, the male leading the female over his spawning site and quivering to solicit egg-laying. Male breeding colour and display are central to mate choice in this flock, and because these are visual signals, the increasing turbidity of modern Lake Victoria is thought to interfere with the female mate-recognition that keeps closely related species reproductively distinct.
Breeding
Haplochromis chilotes is a maternal (ovophilous) mouthbrooder, the universal mode of the Lake Victoria haplochromine flock. The female takes the fertilised eggs into her mouth — commonly using the egg-dummy mechanism typical of the group, snapping at egg-spots on the male's anal fin so that he releases sperm as she collects the clutch — and broods them through hatching while taking no food. Clutches are small, as in most members of this radiation: an aquarium spawning reported by Borstein produced a female holding about 35 fry, which she carried for roughly 24 days; this is consistent with the modest, mouth-limited fecundity (tens of eggs, genus-typical) seen across the flock. After release the female continues to guard the free-swimming fry for a time, allowing them back into her mouth at any disturbance for as long as about a week before they become independent — extended buccal care that is characteristic of these cichlids. The newly released fry are very small and, in captivity, are reared on baby brine shrimp; under good conditions they grow quickly. Although the species is not always easy to bring into spawning condition, keepers report that once a group is settled it breeds readily.
In the aquarium
Haplochromis chilotes reaches hobbyists only occasionally — Victorian rock cichlids are far less established in the trade than Malawi or Tanganyika species — but it has been kept and bred, and several colour forms exist, the Zue Island form being the best known. It is one of the more peaceful Mbipi; experienced keepers report that a full-grown group of about six can be housed in as little as a 40-gallon "breeder" footprint, though more room reduces the squabbling between rival males. As a hard-water lake fish it wants alkaline, moderately hard water (broadly pH 7.5–8.5) at about 73–81 °F, with strong filtration and good oxygenation. The most important décor is rockwork: a structure of stacked stones with caves and crevices gives the fish security and lets males set up territories, and a sand bed lets them express their natural digging. A practical caution from Seehausen is that Lake Victoria haplochromines lose their colour within minutes when they feel exposed — backlit or shadeless tanks produce washed-out, drab fish — so caves should read as genuinely dark refuges, and a dark background helps. The lobed lips tend to shrink in captivity under soft, smooth conditions, so wild-type lip development is rarely fully reproduced indoors. Feeding is undemanding: although a crevice-picking insectivore in the wild, it is not a picky eater and accepts good-quality flake and pellet alongside frozen and live invertebrate foods, which bring out the best colour. Tankmates are best limited to other robust, similarly sized Victorian or comparable haplochromines; mixing closely related Victorian species risks hybridisation, a real concern given how easily this flock interbreeds in tanks. As with all Lake Victoria cichlids, responsible keepers should avoid releasing fish or hybridising the conservation-sensitive wild forms.
Conservation
The IUCN Red List assesses Haplochromis chilotes as Least Concern (assessed 31 March 2010, published 2010; assessors Witte, F., de Zeeuw, M.P. & Brooks, E.), with a population trend listed as stable. That comparatively secure status sets it apart from many members of the Lake Victoria flock, which suffered one of the most severe vertebrate extinction events of the twentieth century: the introduction and explosive spread of the predatory Nile perch (Lates niloticus), combined with eutrophication, declining water clarity and heavy fishing pressure, is estimated to have wiped out or imperilled a large fraction of the lake's endemic haplochromines, with many species assessed as Critically Endangered, Extinct in the Wild, or Extinct. As a rock-associated species, Haplochromis chilotes appears to have fared relatively well — rocky habitats offered some refuge from Nile perch, and several Mbipi persisted or partially recovered as perch numbers later declined — which is reflected in its Least Concern listing. It carries no CITES listing. Even so, the broader pressures on Lake Victoria — eutrophication, turbidity that erodes the visual mate-choice keeping species distinct, and ongoing fishing and habitat change — remain the backdrop against which the long-term security of this and every Victorian endemic should be read.