The effect of cnidoscolus chayamansa McVaugh (1944) in improving stress tolerance in Oreochromis Niloticus (Linnaeus, 1758)

Abstract- Tilapia culture is gaining importance as a candidate species for aquaculture in India in recent days. Many countries had started culturing tilapia several years back. As culture becomes more intensified, chances for occurrence of diseases also increases. Although tilapia is a hardy species, it is seen that stress can become a main factor for onset of disease, particularly at higher temperature. Nowadays Tilapia Lake Virus (TiLV), viral infection is spreading in the tilapia population, apart from bacterial infections that may frequently occur particularly in recirculatory aquaculture systems. Since no particular medicines are available for viral infection, it is better to prevent the disease outbreak. This is possible by strengthening the immune system of fish. Of the many ways to increase the disease resistance of fish, improving the quality of feed by ensuring the availability of the most essential micronutrient that help improve to the health of fish is the main one. In the present study the effect of Cnidoscolus chayamansa in improving the stress tolerance of nile tilapia was analyzed. The experiment comprised of five treatments maintained in triplicate. Of these, one group was maintained as control and other four groups were fed with chaya powder incorporated formulated feed. After 30 days of study, haematological parameters, antioxidant enzyme activity, liver function test and bacterial challenge study were carried out. Since the iron content of chaya is high, the haemoglobin level and haematocrit values were higher when compared to control. Antioxidant enzymes such as SOD, GPx and Catalase were examined. Specific activity of these antioxidant enzymes found to be increased as the concentration of chaya powder increases. Cnidoscolus chayamansa is also rich in ascorbic acid, calcium and potassium. Liver function tests such as SGOT, SGPT and alkaline phosphatase were examined .The level of these enzymes were decreased as the concentration of chaya increases. After 24 hours of bacterial challenge with pathogenic Aeromonas hydrophila, fishes were observed. Control fishes succumbed to Aeromonas infection. None of the treatment fishes died. After challenging study antioxidant enzyme and liver function tests were done. Activity of antioxidant enzymes shows an increment when compared with control fishes. The amount of liver function enzyme was decreased in the blood indicating the better health of liver. Since best results were obtained in T4 in basis of haemoglobin, haematocrit value, antioxidant enzyme activity and liver function tests, it may be concluded that incorporation of Cnidoscolus chayamansa upto 4.5% can definitely improve the health of liver and stress tolerance of fish.