Taxonomy & naming
The species was described in 1977 by the German worker A. Paulo, in the aquarium magazine Das Aquarium, as Pelvicachromis sacrimontis, on the basis of imported aquarium fish from Nigeria. The original description was thin and the type material was not properly fixed, and for many years the name drifted in and out of use: most authors treated sacrimontis as a junior synonym or a regional colour form of the widespread rainbow krib, Pelvicachromis pulcher, and that is how the 'giant krib' was usually labelled in the trade. The matter was settled in 2012, when Anton Lamboj — the foremost specialist on West African cichlids — and Christian Pichler published a paper in Zootaxa 'On the validity of Pelvicachromis sacrimontis Paulo, 1977', in which they designated a neotype, redescribed the species in detail, and confirmed it as distinct from Pelvicachromis pulcher. The neotype (MRAC 86-10-P-102, a 2.5 in male) was taken at Chokoche on the Imo River in Rivers State, southern Nigeria. Eschmeyer's Catalog of Fishes accordingly lists the current valid name as Pelvicachromis sacrimontis Paulo, 1977, with the 2012 neotype designation. The epithet is a small Latin puzzle: sacri (from sacer, holy) plus montis (of the mountain) renders the German surname Heiligenberg — 'holy mountain' — a Latinised tribute by Paulo to the neuroethologist Walter Heiligenberg, who studied cichlid behaviour. The genus sits in the African cichlid subfamily Pseudocrenilabrinae; sacrimontis belongs to the smaller, deeper-bodied core of Pelvicachromis alongside pulcher, taeniatus, subocellatus and roloffi, and was not among the species moved to the new genus Wallaceochromis in 2016.
Morphology
Despite its hobby name, the 'giant' krib is only modestly larger than the common krib. FishBase, following Lamboj & Pichler, gives a maximum of about 3 in standard length; well-fed aquarium fish, measured to the tail tip, are commonly cited at around 4 in total length for males, with females smaller — so it is a stockier, heavier-built krib rather than a dramatically bigger one. Fin counts run to 15 to 17 dorsal spines with 8 to 10 soft rays, three anal spines with 6 to 8 soft rays, and 26 to 27 vertebrae. Lamboj & Pichler diagnose it largely on colour and proportion. The mid-lateral dark band on the body is broad — usually as broad as, or broader than, the pale yellowish band above it — which is one of the clearest pointers separating sacrimontis from the narrower-striped pulcher. Adult males lack the pattern of pale-blue and reddish dots that ornaments the caudal fin of taeniatus and subocellatus, and they lack the dark vertical body bars of the humilis group. The cheeks carry an iridescent bluish-to-turquoise band. As in every krib the female is the showier sex: in spawning dress she rounds her body and flushes the belly an intense purplish-red framed in black, and her dorsal fin lights up — but, diagnostically, without the black margin, yellow submargin and black fin-base of a female pulcher; in sacrimontis the dorsal has no margin, the spiny part is pale to dusky orange and the soft rear part is yellowish to clear. The common 'green' label in the trade comes from the greenish-bronze sheen of well-coloured fish.
Habitat
Pelvicachromis sacrimontis is endemic to southern Nigeria. FishBase summarises its range as the lower Niger and Cross River systems in the south-western — more properly south-eastern — part of the country, and the collection data behind the 2012 redescription place it firmly in the Niger Delta and its neighbouring coastal basins: the neotype came from the Imo River at Chokoche in Rivers State, and paraneotype material spans the delta's tangle of rivers and creeks, including the Sombreiro. This is lowland forest and swamp-forest country — the maze of slow, tea-coloured creeks, marigots and floodplain pools that thread the Niger Delta. The species is a fish of small to medium watercourses and their margins rather than of large open rivers, living among leaf litter, roots, submerged wood and marginal vegetation in shallow, shaded water. Detailed wild water-chemistry measurements specific to sacrimontis are not well published, but the delta habitat and the requirements of its close relatives point to soft, warm, acidic-to-neutral water; aquarium practice settles on roughly 75–79 °F and a pH from the mid-6s to neutral. In the same delta systems it shares the water with the rainbow krib Pelvicachromis pulcher, which is one reason the two were so long confused. Its range lies within the Lower Niger–Benue and the adjacent Cross freshwater ecoregions.
Feeding
Pelvicachromis sacrimontis is a benthic omnivore that forages over the bottom and through the leaf litter of its delta streams. FishBase estimates a trophic level near 3.3, consistent with a diet combining small invertebrates with algal and detrital material. Notably, a wild dietary observation does exist for the genus in this region: in the Sombreiro River of Nigeria, kribs of this complex have been recorded feeding mainly on diatoms — the microscopic algae of the biofilm — which underlines how much of a krib's living comes from grazing aufwuchs rather than from hunting. Alongside that algal and detrital component it takes aquatic insect larvae, micro-crustaceans and other small invertebrates picked from the substrate. In the aquarium it is a hearty, undemanding feeder, taking live and frozen foods — daphnia, brine shrimp, bloodworm, mysis, grindal and white worms — eagerly, and accepting good-quality flake and pellet, but it stays in best condition and colour on a varied diet that keeps a real vegetable component in the mix, as is true of the genus throughout.
Mating
Like all kribs, Pelvicachromis sacrimontis is a monogamous, pair-bonding fish in which the usual cichlid sex roles are reversed and the female leads the courtship. As she ripens, her body shortens and deepens and the belly flushes a vivid black-framed purple-red; she seeks out the male and displays to him in the genus-typical way, arching side-on into a curved, quivering posture that flaunts the coloured belly and the raised dorsal fin, and presses this display until the larger, soberly marked male responds. The pair then select and prepare a cave together — a crevice among roots or rocks, an excavated hollow under wood, or in aquaria a flowerpot or coconut shell. Lamboj & Pichler record a behavioural detail that doubles as a field mark: when a pair is breeding or actively guarding, both sexes show a noticeably more prominent black mid-lateral stripe than usual. This species is rather more assertive and territorial than the common krib, so a settled, securely bonded pair is the basis of successful breeding, and in the aquarium pairs are best left to form naturally from a group rather than arbitrarily matched.
Breeding
Pelvicachromis sacrimontis is a biparental cave spawner, and its reproduction is documented in the 2012 redescription. The female lays her adhesive eggs inside the chosen cave; both parents then guard the clutch, but the female does so the more intensively and more often, tending and fanning the eggs while the male holds the wider territory. The eggs hatch about three days after spawning. The larvae are usually deposited on the floor of the spawning cave — only rarely moved to other nearby caves — and the young become free-swimming around eight or nine days post-hatch, after which they are herded and guarded by both parents for a further five to six weeks. Throughout this brood-care period both adults wear the intensified black mid-lateral stripe noted above. As one of the larger and more robust kribs, sacrimontis is reckoned a relatively willing and productive breeder once a pair is settled, raising substantial broods on the usual first foods — newly hatched brine shrimp, microworm and finely powdered prepared food — supported by clean, warm, soft water and frequent partial changes. As in the genus generally, very soft and acidic water tends to bias the brood toward males, which keepers manage by adjusting hardness and pH if they want a more even sex ratio.
In the aquarium
The giant krib is a rewarding aquarium fish — colourful, characterful and not difficult to keep — but its stronger build and bolder temperament set it apart from the famously easygoing common krib, and it wants a little more room and respect. A single pair is comfortable in a tank of around 31.5–39.5 in length; the layout should be well structured with driftwood, roots, rockwork and several caves or upturned flowerpots, with planting and leaf litter to break sightlines, and ideally a cave small enough that only the female can enter so she can escape an over-keen male. A sand or fine-gravel substrate suits its digging, and subdued, tannin-stained water brings out its best colour. Water should be soft to medium-soft, slightly acidic to neutral, and warm — around 75–81 °F — with breeding best attempted at the softer, more acidic end. The species is more territorial and more boisterous than the everyday krib, so tankmates should be chosen with that in mind: robust mid- and upper-water dither fish such as larger West African tetras, plus loricariid and synodontis-type catfish, work well, while small or very timid fish may be harassed, and bottom-dwellers should be removed before a spawn as they will take eggs and fry. The cardinal rule, as with all kribs, is conspecific restraint: keep only a single compatible pair unless the tank is large and heavily broken up, and be ready to separate a pair if post-spawning aggression flares. It reaches the trade fairly regularly as wild Nigerian imports and tank-bred stock under the 'giant krib' or 'green krib' labels, and is well worth seeking out by anyone who enjoys the common krib and wants its bigger, brighter cousin.
Conservation
Pelvicachromis sacrimontis has not been formally evaluated by the IUCN Red List — its status there is Not Evaluated — and it carries no CITES listing. This reflects in part its long taxonomic limbo: for most of the period in which African freshwater fishes were being assessed, sacrimontis was treated as a synonym or colour form of the common krib rather than as a species needing its own assessment, and it has not yet been re-examined since the 2012 redescription. No quantitative population data are published. The species is, however, restricted to southern Nigeria, and much of its known range lies in the Niger Delta — a region under severe and well-documented environmental pressure from oil extraction and the chronic pollution that accompanies it, alongside deforestation, urban and agricultural expansion, dredging and the siltation and habitat loss that follow. A small-bodied, habitat-specific cichlid confined to delta creeks in one of the most heavily impacted wetlands in Africa is exactly the kind of fish whose security should not be assumed simply because it has not been assessed. A modern Red List evaluation, now that the species is firmly recognised, would be a sensible priority; in the meantime it is fortunate that the fish breeds readily in captivity, which gives the aquarium hobby a real role in maintaining stocks.