Scales, operculum and otoliths: key to a comprehensive understanding of age determination of Crucian carp, Carassius carassius (L.)

The study was undertaken with an objective to determine the age of Crucian carp, Carassius carassius from Dal Lake using scales, operculum and otolith. As age determination in fishes is considered to be essential for fisheries management and understanding life history of different fish species. After being appropriately prepared fish scales, operculum and otoliths were examined under the microscope to establish the age of fish by counting the number of annuli, or year markings. Fish were between 1+ to 2+ years old, with length ranging from 121 to 131 mm and 132 to 169 mm respectively. Significant positive correlations were observed between total length and total weight (R²=0.8128); and between total length and fish age (R²=0.4547). These relationships indicate a proportional increase in weight with length and an age-dependent size increase, respectively. In the present study growth rings or annuli on scales, operculum and otolith were found visible and clearly distinguishable in C. carassius so it has reached an agreement with other studies that these structures are appropriate for age determination.