Taxonomy & naming
Paraphago rostratus was described by the Belgian-British ichthyologist George Albert Boulenger in 1899. It sits in the genus Paraphago within the family Distichodontidae, part of the order Characiformes' African radiation alongside Citharinidae and Alestidae. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the reference for the currently valid combination Paraphago rostratus; no subsequent revision affecting the genus placement is reflected here.
Distichodontidae is a taxonomically and ecologically diverse Congo-basin family that spans detritivores, herbivores, insectivores, piscivores and a small cluster of specialised ectoparasitic fin-eaters (genera such as Belonophago, Eugnathichthys and Phago). Paraphago rostratus is not one of the fin-eating specialists — its feeding ecology places it with the family's invertebrate- and plant-feeding members instead. Given how sparsely documented the species is, that distinction is worth stating plainly rather than assuming it shares the reputation of its more infamous family.
Morphology
Paraphago rostratus is a small characin, reaching a maximum recorded length of around 5 in. Detailed morphological description is not well represented in accessible sources, and specific data on body proportions, fin formulas and colour pattern beyond general characin body shape is sparse for this species — a gap consistent with its Data Deficient conservation status and its near-absence from the aquarium trade and the ichthyological literature alike.
Habitat
The species is endemic to the Democratic Republic of the Congo, restricted to the Central Congo basin and specifically documented from Lake Mai-Ndombe. It inhabits running waters and shallow rivers, and has been recorded both in open water toward the middle of lakes and along shorelines, consistent with a gregarious, shoaling lifestyle rather than a solitary, cover-dependent one.
Water conditions at documented sites run warm and mildly acidic to neutral: roughly 73–79 °F and pH 6.0–7.0, typical of Congo-basin lowland waters. As with much of its biology, finer-grained habitat detail — seasonal movement, substrate preference, vegetation association — is not established in available sources.
Feeding
Paraphago rostratus feeds on invertebrates, small crustaceans and aquatic plant material — an omnivorous, invertebrate-leaning diet rather than the piscivorous or fin-and-scale-eating habit associated with some of its Distichodontidae relatives. This is an important distinction for anyone encountering the species: unlike the family's specialised ectoparasitic fin-eaters, it is not documented as a threat to tankmates' fins or scales.
Mating
Courtship behaviour has not been documented in available sources. What little is recorded about reproduction in this species concerns spawning and egg deposition rather than a described pairing or courtship display; data on this stage of the life cycle is sparse.
Breeding
Paraphago rostratus is oviparous, laying eggs that are scattered onto aquatic plants or pebbles and fertilised externally by the male, with spawning reported in spring and summer in the trade literature that covers it. Breeding in captivity is not established — this is a species that has essentially not been bred at home, consistent with the broader pattern among African distichodontids and citharinids, most of which are egg-scatterers rarely reproduced in the aquarium. No parental care is described.
Given how little is published on this species specifically, prospective breeders should treat any captive-breeding attempt as exploratory rather than following an established protocol.
In the aquarium
Paraphago rostratus is described in the (limited) hobby literature as peaceful and gregarious, doing best in a group and reportedly compatible with other peaceful community fish — a contrast worth flagging clearly against the reputation of some Distichodontidae relatives that do rasp fins and scales. Given its modest maximum size of around 5 in, it does not require the outsized tanks that larger characins in this atlas demand, though as a shoaling species it should still be kept in a proper group rather than singly.
Because the species is only thinly documented and rarely available in the trade, keepers should treat husbandry parameters as a starting point drawn from its native Congo-basin waters — warm, running water in the roughly 73–79 °F and pH 6.0–7.0 range — rather than as a fully worked-out care sheet. It is not commonly encountered outside specialist African-cichlid or Congo-biotope circles.
Conservation
Paraphago rostratus is listed as Data Deficient on the IUCN Red List, assessed on 16 February 2009. Data Deficient reflects a genuine lack of information on population size, trend and threats rather than a finding of safety, and is common among narrow-range Congo-basin endemics that receive little survey effort.
As a species restricted to the Central Congo basin and Lake Mai-Ndombe, it is potentially exposed to the general pressures facing Congo-basin freshwater fish — habitat change, sedimentation and limited but real fishing pressure — though no species-specific threat assessment is available. Given the Data Deficient status, no claim about the species' current safety or risk should be made beyond what the assessment itself states.