Comparative Growth Performance of Genetically Improved, Chinese, and Local Strains of Rainbow Trout (Oncorhynchus mykiss) in Mid-hill Nepal

Aims: This study aimed to evaluate the growth performance of rainbow trout fry (Oncorhynchus mykiss) derived from the best performing families in a previous experiment.

Study Design: Experimental (Original Research Article).

Place and Duration of Study: Fisheries Research Station (FRS), Trishuli Nepal, between April 2021 and June 2021.

Methodology: A total of 2700 fry with similar initial weights were randomly assigned to three groups based on their origin: Farmers Trout (T1:1.39±0.16g), Chinese Trout (T2: 1.40±0.06g), and Genetically Improved Trout (T3: 1.19±0.1g), each group replicated thrice with 300 fish per tank. The parameters assessed were weight gain, feed conversion ratio, and survival rate. All fish were fed farm-made feed for 90 days with fortnightly sampling.

Results: The Genetically Improved trout group exhibited the highest weight gain (14.22±0.51g), followed by the Chinese trout (13.08±0.24g), and Farmers trout (10.77±0.82g) groups (P=.01). The specific growth rate followed a similar trend, with the Genetic group showing the highest value of 4.28±0.08% and the Farmers group showing the lowest value of 3.60±0.07% (P=.01). However, there was no significant difference in the feed conversion ratio among the groups, which ranged from 0.77 to 1.07. Conversely, the Chinese group's fry demonstrated a significantly higher survival rate (77.94±3.63%) compared to the Genetic (72.33±1.09%) and Farmers (59.28±4.6%) groups (P=.02).

Conclusion: The weight gain and growth rate of genetically enhanced rainbow trout is considerably higher and may enhance the production and profitability of the rainbow culture in Nepal. However, the performance of genetically improved trout requires more validation in farmer’s raceways.