Panda Corydoras - Development

Development

Fertile Corydoras panda eggs require approximately 3–4 days development time before hatching, if kept at a temperature of 22°C. This development time will vary with temperature, taking longer in cooler water.

Upon hatching, the fry are four millimetres long, translucent, but already possessing the basic ground colour of the species, and upon close examination, possess fully formed barbels. Even newly hatched fry possess at least some hint of the adult eye patches, and as the fry grow, these patches darken and become more prominent. Even so, at just four millimetres in length, the fry are practically invisible against typical aquarium gravel unless seen to move.

The fry take approximately four weeks to develop to the point where the finfold, a continuous undifferentiated membrane resembling that seen at the posterior of a tadpole, has differentiated into the unpaired fins (dorsal, anal and caudal fins). During this time, size will have increased to approximately eight or nine millimetres, and the fish will begin to develop colour changes leading to that of the adult fish. From this point, the caudal peduncle patch and dorsal fin patch will begin to appear, but the body will also be seen to be covered in fine black 'pepper dots' between these black patches. Only after a period of 10 to 12 weeks, at which point the fish has assumed a size of 12 to 14 millimetres, will the fish attain the colouration of the adult, and be in all respects a perfect miniature of the parents.

Fry of this species are particularly sensitive to changes in water chemistry and to elevated temperatures. While adult fishes can withstand temperatures of 28°C, fry will die of heat stress if exposed to temperatures above 26°C, and their chances of survival are enhanced if the water temperature is kept at 22°C or below. Water changes made to a nursery aquarium during the first 21 days of life of the fry—the critical period during which they manifest the greatest sensitivity to their environment—must be gradual, and the incoming water conditioned to match that of the existing aquarium water where possible before the water change takes place. While the fry are likely to develop best if given infusoria as part of their feeding régime, it is possible to raise fry to adulthood entirely upon prepared foods.