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

Abstract

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^3.03. 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^-1. 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^-1, while the energy content ranged from 4.50 to 11.39 kJ g^-1, 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.

Keywords: Cavefish; Growth; Storage; Triplophysa rosa; VBGF.

Fig. 1

The photo of an individual of Triplophysa rosa

Fig. 2

The length and weight relationships of Triplophysa rosa

Fig. 3

The correlation of age reads from otoliths and vertebrae of Triplophysa rosa

Fig. 4

The von Bertalanffy growth curves of Triplophysa rosa

Fig. 5

Auximetric plot comparing the von Bertalanffy growth parameters among fishes Species other than Triplophysa were extracted from FishBase (July 2022), and the von Bertalanffy growth parameters of Triplophysa other than Triplophysa rosa were quoted from the literature [–45, 47]. Every parameter was transformed by a log10 factor. Triplophysa fish are shown by colored circles, whereas other species are represented by gray circles. On the link between k and L_∞, both linear models (dashed line) and phylogenetic generalized linear models (solid line) were used. The gray lines show relationships among other species, while the red lines show relationships among Triplophysa species. The green lines connect the Φ’ values, the direct indication of growth performance

Fig. 6

Variations in the body compositions with total length of Triplophysa rosa

Fig. 7

Variations in energy content with total length of Triplophysa rosa