In order to investigate the relationship between otolith weight and fish length, 41 specimens of Ponticola bathybius were collected using hand trawl net, from April to May 2016, in the southern part of the Caspian Sea. The weight - length relation for this species was W =4.76 TL – 56.05. The results showed a high correlation between otolith weight and fish length in this species. The results of this study provide a useful tool for estimation of fish biomass from piscivorous animal’s stomach remnants, in trophic relationships in this region.
