Taxonomy & naming
Otopharynx brooksi was named by Michael K. Oliver in 1989, in the account of the genus Otopharynx written for Eccles and Trewavas's monograph on the haplochromine cichlids of Lake Malaŵi; Eschmeyer's Catalog of Fishes lists the authorship as Oliver in Eccles & Trewavas, 1989. The genus Otopharynx Regan, 1920 belongs to the family Cichlidae, subfamily Pseudocrenilabrinae, and to the great endemic 'haplochromine' species flock of Lake Malaŵi. Its defining feature is a melanic colour pattern of three discrete dark blotches: a 'suprapectoral' spot above the pectoral fin, a 'supra-anal' spot on the upper flank near the anal-fin origin, and a spot on the caudal peduncle — a pattern shared with relatives such as Otopharynx lithobates and Otopharynx ovatus. For much of the twentieth century the species now in Otopharynx were scattered through the catch-all genus Haplochromis; Oliver's revision pulled together those sharing the three-spot apomorphy. The specific epithet honours John Langdon Brooks (1920–2000), an evolutionary biologist and limnologist at Yale University. The type locality is Thumbi Island West, in the southwestern arm of the lake near Cape Maclear, the same well-studied rocky-island area that yields many of the region's described cichlids.
Morphology
Otopharynx brooksi is a moderately large, fairly elongate haplochromine reaching about 6 in total length in males, with females somewhat smaller (around 5 in), according to FishBase. It has the generalised, laterally compressed body of a predatory Lake Malaŵi 'hap', with a fairly pointed head and a sizeable, slightly oblique mouth suited to seizing small prey. The genus name Otopharynx ('ear-throat') refers to a pocket or recess in the wall of the pharynx, a feature of the throat anatomy rather than anything visible externally. The most reliable external marks are the three dark melanic blotches that define the genus — suprapectoral, supra-anal and caudal-peduncle — set against a ground colour that in breeding males takes on the metallic blue and yellow tones typical of the flock. As with most members of this species-rich radiation, the detailed live coloration of dominant males is the surest field character, while preserved specimens are separated from close relatives by counts and proportions of the head, jaws and fins.
Habitat
The species is endemic to Lake Malaŵi (Lake Nyasa), the third-largest and second-deepest of the African Great Lakes, and is recorded mainly from the southern part of the lake. FishBase characterises it as a freshwater, demersal fish of the sandy areas near rocks — the so-called 'intermediate' habitat where sand meets rocky outcrops and islands. This transitional zone is a productive one for predatory haps, offering both open sand to patrol and rocky structure that shelters the smaller fishes they hunt. The type series came from Thumbi Island West near Cape Maclear, within the area now protected as Lake Malaŵi National Park. Lake Malaŵi's inshore waters are warm, clear and strongly alkaline, with stable temperatures around the mid-20s Celsius and a high, buffered pH typical of the rift lakes.
Feeding
Otopharynx brooksi is a piscivore: FishBase reports that it feeds on small fishes, consistent with its elongate body, pointed head and grasping mouth. Within the Otopharynx radiation, feeding habits vary — some relatives glean invertebrates or, like Otopharynx ovatus, specialise on the eggs of other cichlids — but brooksi sits at the predatory end, taking the abundant small fishes (including juvenile cichlids) of the intermediate sand-and-rock zone. As a mid-sized hunter patrolling the margin between sand and rock, it occupies a familiar Lake Malaŵi niche, using cover and ambush to pick off prey rather than chasing in open water.
Mating
No dedicated behavioural study of brooksi courtship has been published, but it shares the reproductive biology universal to the Lake Malaŵi haplochromines: maternal mouthbrooding with polygynous, lek-like spawning. By that pattern, mature males develop bright nuptial colours and defend a territory or display site, courting passing females with lateral displays, quivering and fin-spreading. A receptive female lays a small clutch on the substrate and immediately takes the eggs into her mouth; the male's anal-fin 'eggspots' play the classic role in fertilisation, the female snapping at them and drawing in milt. Males contribute only their display and genes, taking no part in brood care — the standard arrangement across the flock, and the safest inference for this species in the absence of direct observation.
Breeding
Breeding has not been documented in detail for Otopharynx brooksi specifically, but as a Lake Malaŵi haplochromine it is a maternal mouthbrooder. The female incubates the fertilised eggs in her buccal cavity for roughly three weeks, during which she does not feed, then releases free-swimming fry that she may continue to shelter in her mouth when danger threatens. Clutches in haps of this size are typically modest — on the order of a few dozen eggs — a trade-off of fecundity for the strong survival advantage that oral incubation confers. The specific clutch size, brooding period and fry behaviour for brooksi remain unrecorded; what is stated here is inferred from the consistent biology of the genus and the wider Malaŵi flock rather than measured for this species.
In the aquarium
Otopharynx brooksi appears occasionally in the aquarium trade — FishBase flags it as of commercial interest both as a food fish and in the ornamental trade — but it is far from a hobby staple, and there is little published keeping or breeding experience specific to it. Any husbandry notes are best extrapolated from comparable predatory Malaŵi haps.
A fish of around 6 in needs a roomy tank with a sand substrate and rockwork that reproduces its natural intermediate zone, giving it open swimming space and the broken cover it favours. Lake Malaŵi water conditions apply: hard, alkaline water (pH about 7.5–8.5), stable temperatures in the mid-20s Celsius, and the excellent filtration and water quality these high-metabolism rift cichlids demand. As a piscivore it should not be housed with fish small enough to be eaten, and like most Malaŵi haps it is best kept with robust, similarly sized tankmates that can absorb the assertiveness of a breeding male. A varied carnivore diet of quality pellets and meaty frozen foods suits it; rich mammalian-based feeds should be avoided, as they are for the flock generally. In short, a manageable but genuinely predatory hap for the keeper with space, not a community fish.
Conservation
Otopharynx brooksi was assessed by the IUCN Red List as Least Concern in 2018. That status reflects a reasonably wide distribution across the southern part of a vast lake and no evidence of a specific threat to the species, rather than detailed monitoring of its population. The broader picture for Lake Malaŵi is more cautionary: the lake holds the richest freshwater fish fauna of any lake on Earth — overwhelmingly endemic — and the 2018 Red List assessment of its fishes found a meaningful fraction at elevated risk, driven by intense artisanal and commercial fishing pressure, habitat degradation and sedimentation in inshore waters. The type locality lies within Lake Malaŵi National Park, a UNESCO World Heritage Site, which affords some protection, though illegal inshore netting is a recurring problem there. As a fairly widespread sand-and-rock predator, brooksi is not currently of conservation concern, but its fortunes are tied to the health of the lake's inshore ecosystem as a whole.