thought to myself, lets have something really weird for the August
2018 factsheet and here it is the only member of the Nematogenyidae
family and a Chilean catfish to boot the "Mountain Catfish"
= dorsal head view
Containing only this single species,
N. inermis. The genus is endemic to some rivers in
Chile. The common name for this species is "Mountain Catfish".
Previously in the Trichomycteridae family and is very rare in
the aquatic hobby. There was a fossil which was found and described
from the Miocene, continental fluviolacustrine deposits of the
upper Cura–Mallín Formation (37–39°S),
Chile (Azpelicueta & Rubilar, 1997). That species was named
as Nematogenys cuivi.
= ventral head view
N. inermis has no adipose
fin and and the caudal fin is short and rounded.
inermis = Line drawing by W.
S. Atkinson from Eigenmann 1927: Pl VII
Flattened head dorsoventrally. Dorsally, a
longitudinal groove is seen between both halves of the epiaxial
musculature and the body thins notoriously towards the caudal region.
They present a wide mouth with small teeth in large quantity. They
have three pairs of barbels; maxilla, nasal and mental. The eyes
are small in size and separated by ample space interorbital. They
have only one dorsal fin, with a narrow base and inserted over the
pelvics. The anal fin is distant from the anus and separated from
the pelvics. The tail fin is large and rounded. This species also
has a large caudal peduncle compressed, tall and thickened dorsal
rim (Ruiz, 1993).
This species is considered very primitive,
mainly because it has three pairs of barbels, opercula and subopérculos
without thorns, thorns of the pectoral fin and dorsal fin a
level of the pelvics. However, studies have shown the reduction
of the jaws that they support the chins and specialication in
the loss of bones like the opisthotic, subopercular, interopercular.
Currently, N. inermis, is a species whose distribution
and abundance is in frank decrease. The main reasons for its
reduction are the direct alteration of its habitat by decrease
of flows, dredging, channeling, fragmentation, alteration of
regimes of flow, sedimentation, deforestation of the riparian
zone and pollution. It is also very vulnerable to predation
by introduced species.
In its native Chile its common name is "Catfish" or
The colouration exhibited by this fish is
yellowish to light brown in the body, with a large amount of irregular
spots, especially on the fins, the belly becomes clearer on the
back (Ruiz, 1993).
There is not much information
on keeping this species in the aquarium but as it was a
former member of the Trichomycteridae family then the husbandry
pertaining to this would adhere but studies indicate that
in captivity they do not accept any kind of food, dying
An aspect of its reproduction indicates that
it belongs to the category of partial synchronism, it is to say,
will spawn once a season. The spawning period would occur in late
spring or at the beginning of summer (Manríquez et al .,
The feeding items for this species are basically
benthic. Studies indicate that in captivity does not accept any
kind of food, dying after months (Manríquez et al ., 1982).
According to Oliver (1949), these fish feed at night, worms and
insects. The examined stomach content reveals that the most frequent
item is Hemiptera, followed in importance by Amphipoda and Diptera
Pertaining to the upper jaw. (maxillary barbels)
Nasal: On top of the head, by the nostrils.
Mental: Pertaining to the chin, on the
lower jaw. (mental barbels)
Dorsal fin: The primary rayed fin(s) on
top of the body
Anal fin: The median, unpaired, ventrally
located fin that lies behind the anus, usually on the posterior
half of the fish.
Pelvic fins: The paired fins, between the
pectorals and the anal fins. (also referred to as ventrals)
Caudal peduncle: The narrow part of a fish's
body to which the caudal or tail fin is attached.
Caudal fin: The tail.
Adipose fin: Fleshy finlike projection
without rays, behind the rayed dorsal fin.
Opisthure: The tip of the vertebral column
which protrudes beyond the caudal fin.
Subocular: Beneath the eye.
Between the preoperculum and the operculum, sometimes very
small, and in some Loricariidae bearing spines.
Greek, nema, -atos = filament + Greek, genys, -yos = face,
M.C.C., 2003. Nematogenyidae
(mountain catfishes). p. 268-269. In R.E. Reis, S.O. Kullander
and C.J. Ferraris, Jr. (eds.) Checklist of the Freshwater
Fishes of South and Central America. Porto Alegre: EDIPUCRS,
Froese, R. and D. Pauly. Editors. 2017.FishBase.
World Wide Web electronic publication. www.fishbase.org, (
Ferraris, C.J. Jr., 2007. Checklist of catfishes,
recent and fossil (Osteichthyes: Siluriformes), and catalogue
of siluriform primary types. Zootaxa 1418:1-628.
Burgess, W.E. 1989 An atlas of freshwater
and marine catfishes. A preliminary survey of the Siluriformes.
T.F.H. Publications, Inc., Neptune City, New Jersey (USA).
First and second: © Iván
S. Atkinson from Eigenmann 1927: Pl VII
inermis, Nematogenys nigricans, Nematogenys pallidus
Isolated localities in Concepción, Rancagua and Angol,
Chile. Formerly widespread throughout much of Central Chile.
Type locality: Chile.
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