Integrated Oyster-Fish Farming for Enhanced Water and Sediment Quality in an Aquaculture System

The filter feeding activities of oysters affect the nutrient removal, enhance water clarity and sediment quality, thereby imparting a potentially significant benefit to the estuarine systems which can have a significant impact on human well-being. This study considered the effect of oysters in improving the water and sediment quality in an integrated fish-oyster aquaculture system. Experiments were carried out from February to November in the Moothakunnam region of the Vembanad lake in the Ernakulam District, Kerala. The study was carried out using four cages (1×1×1m) referred to as treatments, T1, T2, T3 and T4 by integrating fish (Etroplus suratensis) and oysters (Crassostrea madrasensis) in the ratio of 1:0.3, 1:0,5, 1:0.7 and 1:0 respectively. The physico-chemical characteristics of water and sediment samples were determined and compared between the treatments. The water parameters such as DO, BOD, COD, TSS, TDS, ammonia, orthophosphate and silicate and the sediment parameters, pH, salinity, ORP, TOC, TC and TN varied with different treatments and months. However, the contents of nitrite and nitrate of water showed variation only with respect to months. Integrated culture of fish and oysters (T1, T2 and T3) exhibited lower levels of nutrients and organic matter compared to that of monoculture (T4). More breaking results were obtained from treatment, T2, wherein a stocking ratio of 1:0.5 for fish : oysters is maintained which supports the fact that fish and oysters in appropriate proportions leads to an improvement in production and quality of waters.