The current study aimed to prepare silage from poultry slaughterhouse waste using an organic acid fermentation method. The chemical composition of the silage was assessed, with results showing a moisture content of 9.21%, protein content of 59.71%, fat content of 12.81%, ash content of 12.63% and an NFE (nitrogen-free extract) of 5.64%. Amino acid analysis revealed that the silage contained 18 amino acids in a balanced composition of essential and non-essential amino acids, with varying concentrations. Glutamic acid was the most abundant amino acid, measuring 7.11mg per 100mg of protein. Additionally, the study determined the quantity and quality of total fatty acids in the poultry waste silage, identifying 19 fatty acids with varying levels depending on the sample type. Palmitic acid had the highest concentration at 24.1µl per 100µl of oil. Four experimental diets were formulated, three of which included varying levels of silage as a partial substitute for fishmeal: T1 (25% substitution), T2 (50% substitution), and T3 (75% substitution), while the final treatment, C, served as a control with no added silage. The results indicated that T2 diet outperformed the other treatments in terms of growth and nutritional parameters, including final weight, total weight gain, daily growth rate, relative and specific growth rates, feed conversion ratio, protein efficiency ratio, protein intake and overall digestibility. The study demonstrated that poultry slaughterhouse waste silage could be used as a partial replacement for fishmeal, up to 50%, in common carp (Cyprinus carpio L.) diets without any adverse effects on nutritional and growth performance parameters.