The effects of difference temperature on acute ammonia toxicity in juvenile hybrid grouper

Ammonia is a toxic to all vertebrae including fish and can caused a major concerned in aquaculture industries. Ammonia expressed as unionized ammonia and ionized ammonia when in aqueous form. The proportion of unionized and ionized ammonia level in the water are depends on the temperature and pH of the water. In Malaysia, the temperature was rise and fall through all the year due to the hot and cold climate. Therefore, the objective of this study is to determine the different temperature on acute ammonia level in the juvenile hybrid grouper. Eighty juvenile hybrid grouper (TGGG) size around 28.3g with total length of 11.9cm were used to assess their capabilities to respond towards ammonia level and different temperature. All fish were divided into 8 groups; Group A1 (1.5mg/L NH3-N at 29°C), Group A2 (2.5mg/L NH3-N at 29°C), Group A3 (3.5mg/L NH3-N at 29°C), Group B1 (1.5mg/L NH3-N at 25°C), Group B2 (2.5mg/L NH3-N at 25°C), Group B3 (3.5mg/L NH3-N at 25°C). The negative control group was assigned at temperature 25°C and 29°C with no ammonia added. The result showed that the amount of total ammonia increasing by times, but the proportion of the unionized ammonia reducing following times in all treatment groups. In addition, the result also showed that no mortality were observed in temperature group 25°C and 29°C with different level of ammonia. This was due to the ability of the fish in respond and tolerant to the elevated ammonia level in the water. Moreover, the physiological of the fish is believed in converting the higher level of ammonia to less toxic substances, such as glutamine and urea. In conclusion, the metabolism of juvenile hybrid grouper had the ability to tolerate with elevated ammonia level in the water at different temperature