Scales such as fish waste are considered worthless, even though they can be used as raw materials for collagen-making. This fish waste management process also contributes to reducing the problem of environmental pollution due to the disposal of fish waste that is not managed correctly. This study aims to determine the relationship between green knowledge upskilling (GKU) of employees, good manufacturing practice (GMP), and eco-performance (EP). The research site was determined by conducting a census of the 35 personnel at PT Marine Biogel Indonesia in Boyolali. The research model uses structural equations (SEM), and the analysis method uses partial least squares. The results show that GKU has a positive and significant effect on GMP. Second, GKU has a positive and significant effect on EP. Third, GMP has a positive and significant effect on EP. Finally, GKU positively and significantly affects EP mediated by GMP. Implementing eco-friendly production practices can increase the utilization of fishing industry waste on a large scale.