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member of the Heptapteridae family, the "Shrimp catfish" used to be assigned to the family Pimelodidae, and Heptapteridaeinae was a subfamily, which is now been given full family status.

Imparfinis pseudonemacheir

The earliest version of the Heptapteridae family, as currently conceived, goes back to the beginning of the last century when Regan (1911). Based on osteological characters, recognised within the Pimelodidae (in its old conception) a group composed exclusively of Heptapterus, Nannoglanis, Pimelodella, and Rhamdia genera currently included in the family Heptapteridae. One of the diagnostic features used by Regan (1911) - "anterier and posterier rami of parapophysis of fourth vertabra connected at the base only" - is an early definition of one of the most conspicuous synapomorphies for this group (cf Lundberg & McDade, 1986: Lundberg et al. 1991a). However it was only 17 years ago (1986) that Heptapteridae was recognised as a monophyletic on basis of cladistic methodology by Lundberg & McDade, (1986).

Imparfinis pseudonemacheir - dorsal view

This genera has 22 described species recorded with the types species being Imparfinis piperatus Eigenmann & Norris, 1900, with one (I. lineatus) in Central America. Most of them don't grow too big and can be housed with most fish as long as they are not too small with the danger of them being eaten.

Shrimp Catfish

None

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South America: Orinoco and Ucayali River basins. Type locality: Venezuela: Rio Tucuragua, near Caicara, Bolívar.

4.0cm. (1¾ins)

24-28°C (75-83°F)

Slender species. Head depressed dorsally, anterier part of body cylindrical. Posterier part of body compressed laterally. Caudal peduncle being more than twice as deep as wide. The barbels are long with the maxillary barbels reaching the end of the anal fin base, outer mental barbels, reaching the end of the adpressed ventral fins. Inner mental barbels to beyond the pectoral base. Eyes large dorsolateral in position, elliptical with the longest axis being horizontal. The lateral line complete and almost straight without branches, reaching the base of the caudal fin. Caudal fin long, deeply forked, the shortest being half the length of the outer rays; there are seven or eight branched rays, above and below one fully developed simple ray, outside of which there are some progressively and rudimentary simple rays. Adipose fin well developed, not very long and almost triangular in shape.

There is no distinctive colour pattern, but rather diffuse markings, where the elsewhere rather widely spaced large melanophores are closer together: on the dorsal surface of the head, and poorly defined dusky cross bars: one across the nape, one at the base of the dorsal spine, one below the posterier rays of the dorsal fin, one between the dorsal and adipose bases; some blackish at the anterier part of the adipose base, and a large patch below the posterier part of the adipose. Laterally there are four dark patches behind the pectoral fins, below the dorsal fin, below the anterier part of the adipose fin and on the caudal peduncle. Caudal fin pale beige with dusky pigment at its base.

An aquarium with hiding places such as bogwood, rockwork, plants and a sand substrate. A good water flow is recommended with good aeration and filtration. Can be housed with small species such as tetras as their small size does not present a hazard but may eat small fry from other species.

Not recorded.

Sex dimorphism is not present or scarcely developed in heptapterids. Juveniles of most species are miniature replicas of the adults. There are few data on the reproductive cycle of heptapterids, probably due to its reduced importance in commercial fisheries and aquarium imports. These catfishes are externally fertilising and are not known to practice parental care. Amaral et al. (1998) described reproductive females of Pimelodella pappenheimi burying in the clay palsades of the sediments of a small coastal stream in southern Brazil, a behavior adaptation to protect the offspring from being washed away.

Small live, frozen and flake foods.

Lateral line: A sensory line, along the sides of the body.
Caudal fin: Tail
Caudal peduncle: The narrow part of a fish's body to which the caudal or tail fin is attached.
Dorsal fin: The primary rayed fin(s) on top of the body.
Adipose fin: Fleshy finlike projection without rays, behind the rayed dorsal fin.
Ventral fins: The paired fins, between the pectorals and the anal fins.
Pectoral: The paired fins just behind the head.
Maxillary barbels: Pertaining to the upper jaw. (maxillary barbels).
Mental barbels: Pertaining to the chin, on the lower jaw. (mental barbels).
Melanophores: The pigment cells that permit colour change, and the concentration of pigment granules within these cells determine the type of colour that is produced.

Imparfinis: Latin, impar = unequal + Greek, finis, pinna = wing, fin.

Roberto E. Reis, Sven O. Kullander, Carl J. Ferraris: Check List of the Freshwater Fishes of South and Central America. 2003.
Froese, R. and D. Pauly. Editors. 2019.FishBase. World Wide Web electronic publication. www.fishbase.org, ( 12/2019 ).
Ferraris, C.J. Jr., 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa 1418:1-628.
Catfish Study Group UK. I. Fuller, Informastion Sheet no. 13. 2001.

Photo Credits

© Johnny Jensen @ 
Map: Google maps 2020