Effect of Spirulina Meal on Growth Performance, Feed Utilization and Survival in Milkfish (Chanos chanos) Fry

The increasing demand for sustainable aquafeed ingredients has encouraged the evaluation of alternative protein sources to fishmeal. Spirulina meal (SPM), a nutrient-rich microalgal ingredient, has the potential to serve as a fishmeal substitute; however, its effects on milkfish (Chanos chanos) under brackish-water conditions require further investigation. This study evaluated the effects of dietary SPM inclusion on growth performance, feed utilisation and survival of milkfish fry reared at 10 ppt salinity. A 90-day feeding trial was conducted using three experimental diets containing 0% (T1), 20% (T2), and 40% (T3) SPM as a replacement for fishmeal. The experiment comprised three replicate tanks per treatment, with 10 fish per tank. Fish were fed three times daily at 6% of body weight, and growth performance, feed utilisation, survival and water quality were monitored. Significant differences were observed in final body weight, weight gain, percentage weight gain, average daily gain, and specific growth rate among dietary treatments (P < 0.001). Final body weight increased from 10.28 ± 0.11 g in T1 to 12.17 ± 0.12 g in T2 and 13.36 ± 0.12 g in T3. The feed conversion ratio decreased significantly from 1.710 ± 0.020 in T1 to 1.540 ± 0.044 in T3 (P = 0.003), while feed conversion efficiency increased from 58.48 ± 0.69% to 64.97 ± 1.81%. Survival ranged from 80.00 ± 5.00% to 86.67 ± 5.77%, with no significant differences among treatments (P = 0.394). Overall, the results indicate that increasing dietary SPM inclusion up to 40% was associated with improved growth performance and feed utilisation without a statistically significant reduction in survival. Spirulina meal, therefore represents a promising alternative ingredient for milkfish diets under the tested brackish-water conditions.