Optimizing Feed Formulation for Enhanced Growth and Survival Rate in the Nile Tilapia: A Study on the Expression of Growth Hormone Glukokinase (GK) and Glucose-6-Phosphate Dehydrogenase (G6PD) Genes

The Nile tilapia (Oreochromis niloticus) is one of the leading aquaculture commodities worldwide and nationally, supported by rapid growth rates, broad adaptability, and consistent market demand. However, intensified farming practices aimed at increasing production can negatively impact water quality, induce stress, and elevate disease risks, threatening fish health and sustainability. Optimal feed management, including the use of functional feeds such as the black soldier fly (Hermetia illucens) larvae, rich in protein and bioactive compounds, can enhance immune responses and growth performance. Thus, this study aims to optimize feed formulation by substituting fish meal with BSF larvae at levels of 0, 25, 50, and 75%, and evaluate its effects on growth, survival, and the expression of key metabolic genes, namely Glucokinase (GK) and Glucose-6-Phosphate Dehydrogenase (G6PD). A completely randomized design (CRD) was employed to assess parameters including growth performance, FCR, survival rate, and gene expression through RT-qPCR analysis. Results indicated that a 50% BSF substitution (R-50) maintained efficient glucose metabolism, reflected by increased GK expression, while supporting optimal growth and feed efficiency. The 75% BSF formulation (R-75) significantly upregulated G6PD expression and achieved the highest survival rate (84%), demonstrating its potential as an immunostimulant diet to bolster stress resilience and disease resistance. In conclusion, appropriate BSF-based feed formulations can sustainably enhance the hematological and genetic performance of the Nile tilapia, supporting more efficient and environmentally friendly aquaculture practices.