Novel Insights on Biometric Traits of Spinesnout Soldierfish, Ostichthys acanthorhinus Randall, Shimizu & Yamakawa, 1982 (Beryciformes: Holocentridae) from Indian Waters

Biometric indices such as morphometrics, otolith size, length-weight relationships, meristic features, condition factors (relative Kn, Fulton KF, and allometric KA), and form factor (a3.0) are studied for ninety-one individuals of deep-sea Spinesnout Soldierfish, Ostichthys acanthorhinus, for the first time from Indian waters. The morphometric characteristics showed a high coefficient of variation (28–36%) for all the features. The morphometric index revealed that seven characters (standard length, trunk length, anal-fin base length, caudal fin length, body girth, snout length, and post-orbital length) were observed in the intermediate category. The slope (b) value of morphometric relationships ranged from 0.879 to 1.067, with a high coefficient of determination values (r2 = 0.917–0.997). The b value of total length (TL) and total weight (TW) relationship divulges hyperallometric growth (b > 3) and best-fit (r2 = 0.995) relationship. The bond between otolith length (OL) and weight (OW) was established as OW = 0.0029OL3.1701 (r2 = 0.9890), while the TL-OW relationship was determined as OW = 0.0004TL2.2854 (r2 = 0.9842). The calculated Kn and KF ranged from 0.87 to 1.14 and 1.97 to 2.73, respectively. The allometric condition factor proclaimed a higher percentage of fish plumpness. The average a3.0 value of O. acanthorhinus was estimated as 0.0247. The morphometric and biometric information of the species, presented here is the first documentation, that will be instrumental baseline data for the management and conservation efforts across its geographical distribution.