Taxonomy & naming
The species was described in 1896 by Georg Pfeffer, a curator at the Naturhistorisches Museum Hamburg who worked up numerous fish collections sent from German East Africa during the 1890s. The parenthetical form of the authority indicates the species was originally placed in a different genus; the precise original combination is not confirmed in the sources available for this article. It has since settled in Astatotilapia, the broad genus of generalized, small-to-medium mouthbrooding haplochromines that P. H. Greenwood consolidated in his 1979 revision to absorb the many similar riverine cichlids scattered across Africa outside the great lakes. The epithet honours Enrico Hillyer Giglioli (1845–1909), an Italian zoologist and museum director prominent in Italian natural-history collecting of the era. The CARES Preservation Program lists this species under the name Astatotilapia tweddlei; Catalog of Fishes treats tweddlei as a synonym of the earlier gigliolii, and this article follows the currently valid name.
Morphology
Detailed morphometric data specific to Astatotilapia gigliolii are not confirmed in the sources available for this article — data sparse. In common with other Astatotilapia, it is expected to show the typical generalized haplochromine build: a moderately elongate, laterally compressed body, a terminal, unspecialized mouth suited to a broad diet, and the sexual dimorphism characteristic of the genus, with breeding males carrying more intense colour and the anal-fin egg-spots used in courtship, while females and non-breeding fish remain comparatively drab and cryptic.
Habitat
Astatotilapia gigliolii is a wide-ranging riverine and lake-margin cichlid reported across parts of East Africa, with its type material collected in coastal Tanzania. Like most Astatotilapia, it is expected to occupy slow-flowing river reaches, floodplain pools and vegetated margins rather than open, deep lacustrine habitat — the generalist niche typical of the genus across the continent. Specific, sourced figures for temperature, pH or depth range are not available for this pass and are not asserted here.
Feeding
No species-specific dietary study is confirmed in the sources available here. Astatotilapia as a genus are opportunistic omnivores, taking a mix of aquatic invertebrates, algae, detritus and plant material according to what is locally available — a flexible feeding strategy that likely explains the genus's wide distribution across African river systems. A. gigliolii is presumed to follow this general pattern, but the claim is inferential rather than directly documented for this species.
Mating
No courtship behaviour has been documented specifically for Astatotilapia gigliolii. Across the genus, mating follows the classic haplochromine pattern: males are polygynous, establishing and defending small display territories that they advertise to passing females rather than forming pair bonds, with the anal-fin egg-spots playing a central role in triggering the female's spawning and fertilisation sequence. This account is drawn from genus-typical biology rather than from direct observation of the species.
Breeding
Astatotilapia gigliolii is presumed, on genus-wide grounds, to be a maternal (female-only) mouthbrooder, the reproductive mode found throughout Astatotilapia and the wider haplochromine radiation: the female takes the fertilised eggs into her mouth immediately after spawning and incubates them without male assistance until the fry are free-swimming. No clutch size, incubation period or captive-breeding record specific to this species is confirmed in the sources available here — data sparse.
In the aquarium
Astatotilapia gigliolii has no established, documented history in the aquarium hobby comparable to its well-known relative A. burtoni, and specific husbandry guidance for this species cannot be responsibly given without better-sourced information. Riverine Astatotilapia in general tend to be hardy, adaptable and easy to feed, but any keeper encountering this species should treat conditions as provisional and verify against dedicated species reports rather than generic genus assumptions.
Conservation
The CARES Preservation Program lists this species — under the name Astatotilapia tweddlei — as Vulnerable. A specific IUCN Red List assessment is not independently confirmed in the sources available for this article. Unlike the narrow-range lake endemics of the Victoria and Kivu flocks, A. gigliolii is reported across a broad span of East African river systems, so its conservation concern is likely diffuse rather than tied to a single catastrophic event: habitat degradation, water abstraction, siltation and localized overfishing pressure across parts of its range are the plausible drivers, though the specific threats documented for this species are not confirmed here. Maintaining a documented, traceable aquarium population — the purpose of the CARES listing — is a hedge against gaps in wild monitoring across such a wide range.