Oreochromis niloticus immune responses examination: a case study of environmental toxicology

For freshwater fish, Tempe liquid waste (TLW) toxicity is not considered harmful, since it does not cause death and/or physical changes to the fish. In this context, this study aimed to examine the effect of TLW on the immune response and survival of Oreochromis niloticus. As a case of environmental toxicology, this study consisted of 4 treatments that supported three replications each, with various concentrations of TLW (0%, 5%, 10%, and 15%), which was introduced to O. niloticus water media. The parameters, including immune responses (white blood cell - WBC, red blood cell - RBC, hematocrit, and hemoglobin) and survival rate (SR), were evaluated in order to determine the effect of TLW contamination. All data were analyzed via the SPSS program to provide statistical analysis. The results indicated that O. niloticus secreted copious mucus and lost its body pigment in response to TLW treatment as a stress response and avoidance behavior. In contrast, the immune parameters were mostly unaffected after TLW treatment, such as red blood cells (RBC), hemoglobin (Hb), hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) (p > 0.05), except for white blood cells (WBC). White blood cells level of O. niloticus decreased significantly after 30 days of treatment in T3, while T1 and T2 had no distinction from T0. Furthermore, there was a considerable decline in lymphocytes, neutrophils, and phagocytosis activity for T2 and T3. Meanwhile, monocytes and basophils were normal in all treatments as the control group. The best treatments were found at T0 and T1 in SR data, reaching 87%. Therefore, TLW with a high concentration was not suitable for tilapia survival. According to the research findings, O. niloticus immune responses may have been influenced by TLW contamination, which resulted in a decrease in SR.