Taxonomy & naming
Haplochromis cryptogramma was described in 1969 by the British ichthyologist Peter Humphry Greenwood, the foremost student of the Lake Victoria cichlids, together with J. M. Gee, in Part VII of Greenwood's monumental serial 'A revision of the Lake Victoria Haplochromis species (Pisces, Cichlidae)', published in the Bulletin of the British Museum (Natural History), Zoology, volume 18. The original account appears on page 48 with figures 30 and 31. The holotype (BMNH 1968.8.30.197) and twenty-two paratypes are held in the Natural History Museum, London; the type locality is the Bulago–Tavu bank in the Ugandan (northern) part of Lake Victoria, taken from a depth of 50–75 feet (roughly 49–75 ft). The species has remained in Haplochromis as a valid name ever since, but that genus is a vast, admittedly artificial holding pen for hundreds of East African cichlids. Greenwood himself, in his later work, would have placed this midwater predator in the genus Prognathochromis (one of the segregate genera he erected for the Victoria flock), and the name is still sometimes cited in that combination; modern checklists and FishBase retain the conservative Haplochromis heading, which is followed here. As an east-African haplochromine it sits within the subfamily Pseudocrenilabrinae and the great Lake Victoria 'superflock', a clade of several hundred closely related, recently evolved species that is the textbook example of explosive adaptive radiation.
Morphology
This is a small cichlid: the largest recorded specimen measures about 3.5 in in standard length, and most museum material is smaller, so a mature fish is a fish of roughly 3–3.5 in. The body follows the generalised haplochromine plan — moderately elongate and laterally compressed, with the single continuous dorsal fin and the three-spined anal fin typical of the family. The epithet captures the one feature Greenwood and Gee chose to immortalise: cryptogramma means 'hidden line' (Greek kryptos, hidden or secret; gramma, line or mark), and the describers coined it for what they called a 'fancied resemblance' between the broken midlateral longitudinal stripes along the flank and the dots and dashes of Morse code. Like most members of the flock the species would have shown the usual haplochromine sexual dichromatism — drab, silvery, cryptically barred females and juveniles versus more strongly coloured, territorial breeding males bearing the orange or yellow egg-spots (ocelli) on the anal fin that are central to the group's courtship — but the fine details of male nuptial colour were not documented in life and are not reliably on record. Coloration in preserved type material is muted, dominated by the dark longitudinal striping that gives the fish its name.
Habitat
Haplochromis cryptogramma is endemic to Lake Victoria, the largest tropical lake in the world, shared by Tanzania, Uganda and Kenya; the type and best-documented records are from the Ugandan north of the lake, and the species is treated as a Lake Victoria Basin endemic. It is an offshore, relatively deep-living fish by the standards of the flock: FishBase records a depth range of about 30–75 ft, and the type series came from 50–75 feet (49–75 ft). Greenwood and Gee found it in comparatively exposed, open offshore situations over soft mud bottoms rather than among rocks or vegetation. Lake Victoria is a large, shallow, warm equatorial lake; its surface waters are alkaline and well-buffered, with pH generally in the range of about 7.5 to 9 and surface temperatures around 75–81 °F, and the species' offshore habitat lies above bottom waters that, historically, could become seasonally deoxygenated. No in-situ chemistry was published specifically for this species, so the figures used here are the lake-wide values for its depth zone.
Feeding
The species is an insectivore specialising on the immature stages of midges. Greenwood and Gee reported that it feeds on the pupae of chironomid (non-biting midge) flies, which periodically rise from the lake bed in dense aggregations, and that it appears to feed away from the bottom — that is, it intercepts the pupae in midwater as they ascend toward the surface to emerge, rather than grubbing them out of the sediment. This places it among the lake's many 'insectivore' haplochromines, one of the principal trophic guilds into which the Victoria flock partitioned itself. FishBase estimates a trophic level near 3.4, consistent with a small predator on soft-bodied invertebrate prey. Its slender, midwater-hunting form contrasts with the bottom-grubbing and mollusc-crushing specialists of the same flock, and illustrates the fine ecological partitioning — by prey type, water layer and bottom type — that allowed so many closely related cichlids to coexist in one lake.
Mating
No courtship or pair-formation behaviour has been described for Haplochromis cryptogramma specifically, and the account here is drawn from what is well established for the Lake Victoria haplochromine flock to which it belongs. These cichlids are polygynous maternal mouthbrooders with no pair bond: a ripe female visits the small, temporary territories that breeding males establish, and the male courts her with lateral displays and quivering, presenting the conspicuous egg-spots on his anal fin. The female lays a small clutch and takes the eggs into her mouth almost immediately; as she mouths at the male's anal-fin ocelli — which mimic her own eggs — he releases milt, fertilising the clutch inside her mouth. The male contributes nothing further. Whether cryptogramma males held territories on the open mud bottom of its offshore habitat or aggregated in some other way was not recorded.
Breeding
Like essentially all members of the Lake Victoria flock, Haplochromis cryptogramma is a maternal (female) mouthbrooder: the female alone incubates the fertilised eggs and the resulting larvae in her buccal cavity, ceasing to feed for the duration, and continues to shelter the free-swimming fry in her mouth for a period after they can swim. No clutch count was published for this species; Victoria haplochromines of its small size typically produce modest broods on the order of a few dozen eggs (commonly around 20–60), reflecting the trade-off mouthbrooders make between fecundity and the protection of large, well-provisioned young. Parental care is by the female only and ends when the brood is released. There is no documented account of this species spawning, in the wild or in captivity, so these figures are the genus-typical pattern rather than direct observations of cryptogramma.
In the aquarium
Haplochromis cryptogramma is essentially never seen in the aquarium hobby. It is a small, plainly coloured, offshore insectivore known almost entirely from museum specimens, with no established presence in the ornamental trade and no record of it being bred by aquarists. This contrasts sharply with a handful of colourful, rock-dwelling 'Victorian Haps' (such as the species marketed as the 'Zebra Obliquidens' or various Astatotilapia and Pundamilia) that hobbyists do keep and breed in conservation-minded programmes. Were it ever maintained, it would need the conditions of its native lake — hard, alkaline water (pH roughly 7.5–9), temperatures around 75–81 °F, a large footprint with open swimming space over a sand or fine substrate rather than a rockwork tank, and the polygynous one-male, several-females stocking that suits maternal mouthbrooders. In practice, no such husbandry experience exists for this particular fish, and the honest statement is that it is a fish of the scientific record, not of the home aquarium.
Conservation
The IUCN Red List assesses Haplochromis cryptogramma as Data Deficient (assessed 31 March 2010 by F. Witte and M. P. de Zeeuw, published 2010), reflecting the genuine uncertainty about whether and where the species still survives; its population trend is listed as unknown and its range is given within Uganda's portion of Lake Victoria. That uncertainty is the central conservation fact. From the late 1970s into the 1980s the upsurge of the introduced Nile perch (Lates niloticus), compounded by eutrophication, deoxygenation of deeper water, and intensifying fisheries, caused a catastrophic collapse of Lake Victoria's haplochromine cichlids — by many estimates well over 200 species were lost or driven to the brink, the largest mass extinction of vertebrates attributed to a single cause in modern times. Offshore, deeper-living insectivores such as cryptogramma, whose midwater foraging zone overlapped directly with the perch and with the spreading hypoxic bottom water, were among the hardest hit; Eschmeyer's Catalog of Fishes flatly records the species' status in the lake as 'extinct'. Whether it persists in some refuge is unresolved, which is precisely why the IUCN withholds a definitive category. Its fate is inseparable from the broader, ongoing degradation of the Lake Victoria ecosystem.