Ontogeny of skeletal ossification in Labeo calbasu (Hamilton, 1822) using differential fluorescence staining technique

The present study was carried out to study the larval skeletal development in Labeo calbasu by using a modified double skeletal staining technique with Alizarin red and Alcian blue. The larval samples were obtained after induced breeding of wild L. calbasu germplasm from the River Ganga. Samples from 2 to 20 dph (day post hatching) were preserved in 4% neutral phosphate buffered formalin solution. Alizarin red and Alcian blue were used to stain the bony and cartilage parts of the skeleton, respectively. The size of the specimens ranged from 6.6 ± 0.16 to 15.6 ± 1.15 mm. The development of skeleton was observed at very early stages. A straight notochord throughout its length and origin of caudal fin rays were seen on 2 dph. The ventral spines, unbranched caudal fin rays and hypurals at ventral side of notochord were clearly visible from 4 dph. Most of the head skeletal elements and vertebral column with vertebral centrum and neural spines started appearing at 4 dph. The dorsal and caudal fins with branched rays and the opercular and jaw bones started ossifying between 10 and 20 dph. The present study gives an idea about the skeletal development process as well as detects the skeletal abnormalities in Indian major carp, L. calbasu.