DETERMINATION OF IMMUNOSTIMULANT DOSE RANGE AND THE BEST SOAKING TIME DURATIONTO THE PHENOLIC CRUDE EXTRACT BEFORE Aeromonas sp. CHALLENGE TEST USING LC50

Immunostimulatory dose given to the fish to be precise, should not be less and should not be excessive. This is because the immunostimulatory properties which can only work at the optimal dose. Therefore, the method for determining the dosage and administration techniques immunostimulatory should be studied in depth. Research on the determination of the dose and the best maceration time on the crude extract phenol Gracilaria sp. using LC₅₀ is intended to determine how best dose and how long it's best used in the immersion process to extract range dose used is 1 g/l; 1,5 g/l; 2 g/l; 3 g/l; 4 g/l and 5 g/l. The results of these observations indicate that doses ≥ 3 g/l has a 10-hour LC₅₀. While the dose ≤ 3 g/l has a 14-hour LC₅₀. However, further research is continued in the time range for prolonged submersion namely 10, 12 and 14 hours. The results showed the soaking time 12 hours showed LC₅₀ 15 hours. It concluded that the dose that can be used to test immunostimulant is 1, 1.5 and 3 g/l with a soaking time of less than 12 hours.