A Comparative Study on Growth Rates and Length-weight Relationships of Snow Trout (Schizothorax sp.) from Rasuwa, Nuwakot, and Okhaldhunga Districts of Nepal

Aims: Snow trout (Schizothorax spp.) are vital to Nepal's aquatic biodiversity and economy, yet little research has addressed their growth potential under controlled conditions. This study aimed to evaluate the growth performance of snow trout from three regions of Nepal (Okhaldhunga, Nuwakot, and Rasuwa) in captivity.

Study Design: Original Research Article.

Place and Duration of Study: Fisheries Research Station (FRS), Trishuli Nepal, between August 18 November 24, 2023.

Methodology: Schizothorax species were collected from Okhaldhunga, Nuwakot, and Rasuwa districts and acclimated to the environment of the FRS in three separate raceways prior to the feeding trial. From each location, a population of 450 apparently healthy and uniform sized snow trout (initial weight: 20.00 + 1.2g) were then distributed into 3 raceway tanks, altogether 9 raceways for 3 groups, feeding upon the commercial feed (48% crude protein) in the form of dough at 3% of the body weight for 90 days. At the end of the feeding trial, growth parameters, including weight gain, specific growth rate (SGR), condition factor (K) and Length-weight relationship (LWR) were measured. Survival rate and water quality parameters were also measured. Statistical analysis for group’s means differences was conducted using one-way ANOVA in R Studio for Windows at a 5% level of significance.

Results: Results indicated Fish from Nuwakot exhibited the highest weight gain (3.61 ± 1.82 g) and SGR (0.23 ± 0.12% per day), though these differences were not statistically significant (P >0.05). The condition factor (K) was highest for Rasuwa fish (0.98), followed by Nuwakot (0.97) and Okhaldhunga (0.97) (P >0.05), indicating that the fish were relatively thin, possibly due to poor nutrition or stressful conditions. The LWR analysis revealed high length-weight correlations for all groups, with Rasuwa fish exhibiting a positive allometric growth pattern (b=3.02), whereas Okhaldhunga (b=2.93) and Nuwakot (b=2.94) fish showed negative allometric growth patterns. This may suggest that snow trotu from Rasuwa were in relatively good physiological condition and adapting well to the rearing conditions at the FRS. Although with no statistical difference, the survival rate was highest for fish from Nuwakot (86.67%), followed by Rasuwa (80.00%) and Okhaldhunga (77.33%) (P >0.05). This may indicate the adequacy of the water quality (average temperature 11.75 ± 0.42℃, dissolved oxygen more than 7 mg/L, and pH 7.71 ± 0.16) maintained during the study.

Conclusion: The findings suggest that while the snow trout demonstrated the ability to survive yet grow slowly under captivity, their growth performance may be significantly enhanced by optimizing rearing conditions, particularly slightly higher water temperature. This study underscores the need for targeted improvements in aquaculture practices to support the effective domestication and conservation of snow trout in Nepal.