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Physopyxis lyra  Cope, 1872


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 = pectoral fin view

 

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.

 

 

Characteristics

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.

 

Colour
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.

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

Breeding
Not reported.

Sexual Diferences

Not known.

 

Feeding

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


Etymology
Physopyxis : Physa = bellows; pyxix = box.

References

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.
Sandford M. August 1984: Introduction to the Doradidae, from David Sands, Catfishes of the World Vol. 4 Aspredinidae, Doradidae & Loracariidae. Dunure Publications 1985.
Ferraris, C.J. Jr., 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa 1418:1-628.

Glossary

Girdle: The bony or cartilaginous skeletal arch supporting the pectoral fins.
Dorsal fin: is defined as the medial fin on top of the back.
Coracoid : Middle and lower section of the pectoral girdle.

Serrate : pertaining to the upper jaw. (maxillary barbels)

Pectoral : The paired fins after head and before anal fin.
Caudal peduncle : The area between the dorsal fin and the tail.
Scapular : The shoulder region.
Abdomen :
Belly, the ventral side of the fish surrounding the cavity containing the digestive and reproductive organs.

 

Photo Credits

Allan James @ ScotCat

 

Factsheet 181

Synonyms:
None   
Common Name:
None
Family:
Doradidae
Subfamily:
 
Distribution:
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).
Size: 
3.5cm. (1½ins)
Temp:
23-26°C (73-79°F)
pH.:
6.5 - 7.0.
Donation:
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                                                                                                                                           Factsheet 181 = updated July 11, 2017 , © ScotCat 1997-2017 Go to Top