Corydoras petracinii
Etymology
Corydoras: from the Ancient Greek κόρυς (korus), meaning ‘helmet’, and δορά (dora), meaning ‘skin, hide of an animal’, in allusion to the rows of bony plates on the flanks of genus members.
petracinii: named for Roberto Petracini, “Argentine fishkeeper, who for decades has been contributing to the development, knowledge and diffusion of Argentinean and South (and Central) American fishkeeping hobby”.
Classification
Order: Siluriformes Family: Callichthyidae
Distribution
Known only from a single locality in the Lomas de Medeiros hills, Río San Lorenzo watershed, Salta province, northwestern Argentina. The San Lorenzo is a tributary within the Río Juramento system, itself an affluent of the upper Río Paraná basin.
Type locality is ‘Small stream, 200 meters from its ending into the San Lorenzo River, 24°47’08″S, 65°28’10″W, Finca Las Costas, around Salta city, Argentina, elevation 1222 meters’.
Habitat
The only known locality comprises a nameless ephemeral stream with a rocky substrate which runs almost dry for large portions of the year, but flows swiftly during the summer wet season. The lower stretches contain permanent water, while further upstream fishes are able to survive in pools which form in deeper areas during the dry period.
Sympatric fish species include Corydoras cf. paleatus, Heptapterus mustelinus, Hoplias malabaricus, and an unidentified Jenynsia sp.
The stream is under great ecological pressure due to its proximity to the city of Salta, construction of new roads in the area, and dumping of refuse.
Maximum Standard Length
30 – 38 mm.
Aquarium SizeTop ↑
Base dimensi0ns of 60 ∗ 30 cm or larger should be adequate.
Maintenance
Ideally use a substrate of fine sand, although rounded gravel is an acceptable alternative provided that it is kept scrupulously clean.
Other décor is largely down to personal choice, but some cover should be provided to give the fish security. In the case of C. petracinii some water-worn rocks would seem appropriate.
A high level of oxygenation and close attention to water quality and temperature should be considered mandatory given its natural habitat.
Water Conditions
Temperature: 10 – 20 °C
pH: 7.0 – 8.0
Hardness: 179 – 357 ppm
Diet
Corydoras spp. are foraging omnivores, and most will accept sinking dried foods as well as small live and frozen varieties such as chironomid larvae (bloodworm), Tubifex, etc.
Feeding a varied diet will ensure the fish are in optimum condition.
NotesTop ↑
C. petracinii is not currently in the aquarium hobby, and unlikely to be collected for commercial purposes given its natural range and habitat.
The species can be distinguished from all congeners by the following combination of characters: 23 dorsolateral body plates; 21 ventrolateral body plates; eyes small, measuring 13.2 – 17.3 % HL; body moderately elongate, depth 27.4 – 33.1 % SL; dorsal-fin spine length 19.5 – 12.6 % SL; pectoral-fin spine length 19.6 – 16.6 % SL; flank with 5-7 separate squarish blotches at the junction between the body plates; caudal fin slightly emarginate and hyaline, with a series of dark blotches forming 3 or 4 irregular vertical bands; pectoral, pelvic, and anal fins translucent with no dark markings.
It also exhibits morphological adaptations to an existence among rocks in a flowing environment, such as a cryptic colour pattern, reduced spine length in the dorsal and pectoral fins, ventrally-oriented pectoral fins, slightly emarginate caudal-fin, and reduced body depth.
Reduced fin spines and body depth are typical features associated with the related genus Aspidoras, but the cranial morphology of C. petracinii is typical of Corydoras with no foramen in the supraoccipital, for example.
The genus Corydoras is included in the family Callichthyidae, of which members are often referred to collectively as ‘armoured’ or ‘mailed’ catfishes group due to the presence of bony plates in place of scales on the body.
Their taxonomy can be confusing, and numerous undescribed species are also thought to exist. Fish of unconfirmed identification entering the aquarium hobby are therefore typically assigned a ‘C’ or ‘CW’ number for purposes of reference and organisation.
They are facultative air breathers and possess a modified, highly vascularised intestine which has evolved to facilitate uptake of atmospheric oxygen and aid survival in oxygen-deprived environments. In the aquarium you’ll occasionally see them rising to the surface to take in gulps of air.
The stiffened pectoral-fin spines are capable of piercing human skin and a ‘sting’ can be very painful indeed, so care should be exercised when handling them.
It is thought that secretions from the axillary glands at the base of each spine may even be mildly toxic or venomous.
Thanks to Pablo Calviño.
References
- Calviño, P. A. and F. Alonso, 2010 - Revista del Museo Argentino de Ciencias Naturales 11(2): 199-214
Two new species of the genus Corydoras (Ostariophysi: Siluriformes: Callichthyidae) from northwestern Argentina, and redescription of C. micracanthus Regan, 1912.
