Inclusion of Spirulina in Floating Fish Feed Production: Protein and Physical Quality

The objective of this study was to investigate effects of Spirulina meal (SM) inclusion in fish feed formulations on their physical and protein content. Four formulations of fish feed were carried out i.e. a control diet with fishmeal (FM) as the single protein source and three others formulations containing Spirulina meal (SM) ingredient in different ratios of FM: SM (w/w) namely 75:25; 50:50 and 25:75 (w/w). All the formulations were processed into pellets using an extruder with a 600 rpm screw speed, 100 °C barrel temperature, and 3 mm diameter of dies. The dried pellets were then evaluated with respect to the protein content and physical properties i.e. expansion ratio, unit density, floatability and hardness. In general, the most optimum pellet formulation was found at the ratio of 25:75 (FM: SM) ingredients resulted in pellet with higher protein (38.89%) and expand ratio (1.65 fold), the lowest unit density (0.473 mg/mm3), the highest floatability (100%) and less hardness (32.53 N). Therefore, formulation of floating fish feed included with Spirulina are an option for improving its protein content and physical properties.