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 his month (July 2011) we visit a not too well known member of the Doradidae family with the unusual trait for the dorads of being very small, bordering on the minute.

Physopyxis lyra

This small species is usually found in places with accumulated organic debris, like dense meshes of roots of floating macrophytes that are abundant in rivers with turbid water. Specimens also can be found among submersed leaf litter and among root mats of riparian plants, like Symmeria paniculata (Polygonaceae).

Physopyxis lyra - view of long pectoral fin

Best to purchase this species in good numbers with 5 or 6 specimens being a good start. Keeping Physopyxis lyra does not present too many problems but they do take a time to acclimatise to the conditions of the aquarium and you may find that one or two will just die for no apparent reason in the first month of purchase, but they should settle down after this period.

The aquarium should have a sand substrate as they do like to lie under the sand and also around plant roots, so planting in the tank would be a good idea.

There are three species in this genera, P. ananas, P. cristata and the more well known P. lyra with the first two being described by Sousa and Py-Daniel (2005). Physopyxis lyra differs from the other species of the genus by possessing a single row of spines on the lateral plates and a strong scapular girdle with long, broad coracoid processes having distal tips enlarged and divergent. outwards following expansion of process. Dorsal and pectoral spines strongly ossified. Dorsal spine pentagonal in cross-section with longitudinal groove along each lateral side, serrate along basal portion of anterior margin, posterior margin smooth. Pectoral spine well developed, depressed and curved, its tip usually reaching anal-fin origin.

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South America: Amazon River basin, Peru and Brazil. Type locality: Amazon. Described in more detail in Cope (1872a: 273, pl. 5, figs. 1a–1c), with locality as Ambyiacu River, Ecuador (now Peru).

3.5cm. (1½ins)

23-26c (73-79f)

6.5-7.0.

Differs from the other species of the genus by possessing a single row of spines on the lateral plates and a strong scapular girdle with long, broad coracoid processes having distal tips enlarged and divergent. outwards following expansion of process. Dorsal and pectoral spines strongly ossified. Dorsal spine pentagonal in cross-section with longitudinal groove along each lateral side, serrate along basal portion of anterior margin, posterior margin smooth. Pectoral spine well developed, depressed and curved, its tip usually reaching anal-fin origin.

Body ground colour tan with brown blotches and spots. Head usually more pigmented than body. Three or four dark brown irregular saddles on dorsum extending onto sides as full or partial bars: anteriormost at base of dorsal fin and usually reaching to lateral line; second from adipose fin to anal fin; third at beginning of caudal peduncle, and fourth at base of caudal fin rays. Last two bars may be joined into one that covers entire caudal peduncle. Barbels tan with brown transverse bands along its entire length. All fins similar in appearance, with dark transverse bands across rays and membranes separated by unpigmented interspaces. Dorsal and pectoral spines with unpigmented tips. Spines and rays with brown transverse bands. Ventral surface variably pigmented, light or dark, with chromatophores regularly spaced over abdomen and scapular bridge.

Inofensive catfish which are largely ignored in the aquarium due to the bony scutes and rugged pectoral fins.

Not reported.

Will eat most prepared foods such as sunken flake and tablet foods but has a liking for frozen bloodworm.

Physopyxis: Physa = bellows; pyxix = box.

Ferraris, C.J. Jr., 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa 1418:1-628.
Sandford M. August 1984: Introduction to the Doradidae, from David Sands, Catfishes of the World Vol. 4 Aspredinidae, Doradidae & Loracariidae. Dunure Publications 1985.
Sousa, L.M. and L.H. Rapp Py-Daniel 2005 Description of two new species of Physopyxis and redescription of P. lyra (Siluriformes: Doradidae). Neotrop. Ichthyol. 3(4):625-636.

Photo Credits

©  Allan James @