Relationship between fish size and otolith characteristics of two gobid species from the Eastern Arabian sea, India

Trypauchen vagina (Bloch & Schneider, 1801) and Odontamblyopus roseus (Valenciennes, 1837), were morphologically similar. The total length and total weight relationship of both species showed a negatively allometric growth. Due to their morphological similarity, these species were generally regarded as a single species. Therefore, the present study was carried out to distinguish these species. The relationships between otolith parameters (length, weight, perimeter, width, area, roundness, circularity, ellipticity, rectangularity and aspect ratio) and fish size (total length and total weight) of T. vagina (Bloch & Schneider, 1801) and pattern, while length and area of otoliths of both species revealed highly positive correlation at significant P value (t-test, P<0.05). The extracted data fitted well to the regression model for area and width of otolith to otolith length of T. vagina and area, width and weight of otolith to otolith length of O. roseus. These relationships can be used as a helpful tool in predicting fish size from the otoliths, calculating the biomass of these fish species and also for taxonomic discrimination of the species, when two species were morphologically similar.