Age, growth, and energy storage of the subterranean fish Triplophysa rosa (Cypriniformes: Nemacheilidae) from Chongqing, China.

Background: This study explores the age, growth, and energy storage of Triplophysa rosa, a troglobitic cavefish. A total of 102 wild T. rosa specimens were collected in Wulong County, Chongqing, China, between 2018 and 2022, with otoliths used for age determination.

Results: The earliest mature individuals were determined to be 4.8 years old, while the maximum ages for females and males were estimated at 15.8 years and 12.2 years, respectively. The length (L, cm)-weight (W, g) relationship was found to be the same for both sexes, following the eq. W = 0.0046 L. Von Bertalanffy growth models were applied to the total length-at-age data, resulting in an asymptotic length of 23.4 cm and a K-parameter of 0.060 year. The body content of protein, ash, and glycogen did not show a significant correlation with the total length of T. rosa. However, both lipid and energy content exhibited a significant increase with total length. The lipid content ranged from 40.5 to 167.1 mg g, while the energy content ranged from 4.50 to 11.39 kJ g, indicating high storage features of T. rosa.

Conclusions: The results affirm that T. rosa exhibits life traits conducive to its population dynamics in cave conditions, characterized by slow growth, small size, and high lipid energy storage.