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Hisonotus aky (Azpelicueta, Casciotta, Almirón & Koerber, 2004)

Image contributors to this species:

Paul Dixon (2) Ingo Seidel (2) Felipe Cantera (1)

ScotCat Sources:

Factsheet Etymology = Genus

Other Sources:

Fishbase  Google Search  All Catfish Species Inventory  Catalog of Fishes

Relevant Information:

Hisonotus aky (Azpelicueta, Casciotta, Almirón & Körber, 2004) was originally described in Epactionotus Reis & Schaefer, 1998 because of its supposed possession of three synapomorphies proposed for that genus: neural spine of seventh vertebra not contacting nuchal plate dorsally (contacting unpaired predorsal plates), first dorsal proximal radial contacting the eighth vertebral centrum, and absence of an expanded fleshy flap on the dorsal surface of the first pelvic-fin ray in males. Also, Hisonotus aky possesses one of the additional diagnostic characters of Epactionotus: longitudinal light stripes on dorsal surface of head. However, the examination of type specimens of Epactionotus aky indicates the absence of most diagnostic features for the genus. Aquarium Care: Will feed on flake, algae, tablet foods and algae wafers and they lay their eggs on plant leaves. They rest on aquatic vegetation in the aquarium and the less light in the tank the darker they become. Provide a current in your tank for this species as they come from swift flowing waters. Remarks: According to Evers et al, they are only found in a small area in the Rio Uruguay drainage in the Fortaleza Creek, close to the city of Paraiso. This species has been bred by image contributor Paul Dixon and is shown here. The following summary is from AZPELLICUETA et al (2004). Epactionotus (Hisonotus) aky is diagnosed by the following combination of characters: 1) 21 to 23 lateral plates; 2) light stripes extended from snout tip to supraoccipital level; 3) caudal fin with dark vertical stripes; 4) ventral surface of body completely covered by small platelets; 5) 1-4 feeble serrae on distal portion of pectoral spine posterior margin.

Common Name:

Green Oto


Epactionotus aky




Argentina: Yabotí-Guazú basin, Uruguay River system, Misiones. Type locality: Argentina, Misiones, Río Uruguay basin, Arroyo Garibaldi (26º38'46.1"S, 53º59'55"W).


4.5cm. (1¾ins)


18-24°c (63-75°f.)




Evers, H.-G. & I.Seidel: Mergus, Baensch Catfish Atlas Volume 1, 1st English edn., 2005. Pp.944.
Ferraris, C.J. Jr., 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa 1418:1-628.
Azpellicueta, Casciotta, Almiron, & S. Korber, 2004, A new species of Otothyrini (Siluriformes: Loricariidae: Hypoptopomatinae) from the Río Uruguay basin, Argentina.
Tiago Pinto Carvalho; The species of Hisonotus (Siluriformes: Loricariidae: Hypoptopomatinae) of the Rio Uruguay basin, southeastern South America in: A new species of Hisonotus (Siluriformes: Loricariidae: Hypoptopomatinae) from the Laguna dos Patos Basin, Southern Brazil.



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