PHYSIOLOGICAL RESPONSES OF COBIA Rachycentron canadum JUVENILE FEED WITH MICROBIAL FLOCS AND MICROALGE Spirulina platensis AFTER FRESH WATER BATHING

Cobia (Rachycentron canadum) is a one of species candidate for mariculture industry in the world. Like the other fish, cobia is sensitive and easy to stress due to culture activities. The objective of the research was to know physiological responses (stress) of cobia juvenile after fresh water bathing. Cobia juvenile was fed with different microbial flock combination with microalgae Spirulina platensis (MFMS) as follows: 0%, 15%, 30%, and 45% as along as 40 days rearing. Response analysis was done through measurement of glucose and cortisol content before treatment (0 hour) and after (1, 2, 4, 6, and 24 hours). The results showed that cortisol concentration was elevated after 1 hour except for 30 % MFMS that was increased after 2 hours. Elevated concentration of glucose as stress hormone response also happen after 1 hour with maximum elevation at second hour except for 45 % MFMS that was elevated at second hour after freshwater bathing. In general, cobia juvenile fed with feed containing MFMS has stress resistant to any treatment

Key words: Cobia, microbial floc, microalgae Spirulina, glucose, cortisol, stress