Corydoras gladysae
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.
gladysae: named in honour of Gladys Ana María Monasterio, ichthyologist at the Universidad Nacional de Salta (UNSa), who first collected this species and “for more than 20 years has been contributing to the knowledge of the diversity, distribution and biology of fishes in the Salta province, Argentina”.
Classification
Callichthyidae
Distribution
Currently known only from two localities within the Río Calchaquí watershed in Salta province, northwestern Argentina. The Calchaquí is a tributary within the upper Río Paraná basin.
Type locality is ‘Calchaquí River, 25°02’59″S, 66°06’25” W, Payogasta, Cachi Department, Salta Province, Argentina, elevation 2430 meters’.
Habitat
The Río Calchaquí rises at almost 6000 m AMSL and flows swiftly through a mountainous valley where it is largely fed by snow melt. The climate is semi-arid and cool with an air temperature of 12-18°C, while rainfall is largely concentrated during summer when the flow can be torrential. The water is hard and rich in salts, with pH measured at 8.04 during the month of August. Aquatic vegetation and filamentous algae grow around the margins and in tributaries.
Not many fishes have adapted to survive these conditions, but those that have are largely endemic and often restricted to particular stretches of the river. Species collected alongside C. gladysae include Bryconamericus rubropictus, Ixinandria steinbachi, Heptapterus mustelinus, Jenynsia maculata and Trichomycterus spegazzinii, plus the introduced predator Onchorhyncus mykiss which may be pressurising communities of small, native species.
Maximum Standard Length
30 – 37.5 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. gladysae 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: 8 – 16 °C
pH: 7.5 – 8.5
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. gladysae is not currently present in the aquarium hobby, and unlikely to be collected for commercial purposes given its natural range and habitat.
The species be distinguished from all congeners by the following combination of unique characters: ossified portion of dorsal spine very short, measuring 7.6 – 10.6% SL (mean 9.2%); pectoral-fin spines short, measuring 11.9 – 17.4% SL (mean 14.8%); caudal-fin slightly emarginate.
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. gladysae 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.
