Balance of ecosystem is being disturbed due to many factors and environmental pollution and many other human activities. Saline soils and water are causing huge disasters in agriculture and many other disciplines. Salinity also effects survival, growth and distribution of many aquatic organisms1. Any changings in salinity leads towards various physiological processes in organisms2. Marine life specifically fishes have to face a lot of troubles with amplification of pollution as well as salinity. Industrial and agricultural revolution has caused acidic or alkaline water condition. Alkaline water towards amplification in the plasma ammonia level3. Inspite of the fact; many fishes exhibit some degree of tolerance, optimal salinity levels for survival, growth and production competence5, mortality rates are being accelerated. Therefore, optimum salinity level for each commercial fish species should be evaluated in order to save this precious life.
The Gurami Sago Osphronemus goramy (O. goramy) is herbivorous freshwater fish species which can grows rapidly in the brackish water (more salinity than fresh water); found in Lima Puluh Kota District, West Sumatra-Indonesia. The O. goramy has been recognized as one of the best prospects for a semi-commercial scale culture in Indonesia. These fish willingly accept pelleted diets and show endurance towards poor water quality and perform well in lakes and freshwater ponds6.
A study was conducted for 60days; in which two independent experiments were performed to evaluate the impacts of salinity on survival and growth of juvenile O. goramy. Assessment of the median experiment and lethal salinity (MLS-5096 h) and in 2nd test, the survival and growth at different sub-lethal salinities were determined. In MLS-5096 h study 0.0, 4.0, 8.0, 12.0 and 16.0 ppt salinities were utilized to check the salinity tolerance range. For that reason, a definitive salinity tolerance test was performed in next phase to find out exact median lethal salinity by directly transferring the test species to 13.0, 14.0, 15.0 and 16.0 ppt salinity for 96 h. The median lethal salinity of O. goramy was predicted at 14.0 ppt. In the second experiment, survival and growth of the O. goramy were recorded at salinities 4.0, 8.0 and 12.0 ppt along with 0.0 ppt as control during 60 days.
In this experiment; Osigni goramy showed lowest final average weight at 12.0 ppt salinity and considerably maximum weight at 4.0 ppt salinity. Highest SGR and weight gain were evaluated at 4.0 ppt followed by 0 ppt, 8 ppt and 12 ppt salinity. It was noted that survival rate of O. goramy varied between 76.45% (at 0.0 ppt) and 66.66% (at 12.0 ppt). Conclusively, the O. goramy grew and survived satisfactorily at 0.0 to12.0 ppt salinities, which showed that the species can be cultured commercially in brackish water, and many abandoned shrimp ponds in Indonesia.
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17 November, 2019