Extensive low lying areas of the Cochin Backwater peripheries at its lower reaches are bunded into interconnected ponds for paddy-cum-prawn culture. Results of a study of two representative ponds are reported. The ponds under study were found to be rich in nutrients and primary production and have a detritus dominated simple food chain aided by a substratum predominantly of fine sand, silt and clay, rich in organic content and benthos. These shallow, semienclosed systems have temperature between 29 degrees and 35 degrees C during the main prawn culture season from December to April and provide ecological conditions distinct in many respects from that of the main backwater. They are given a high rating in terms of their suitability for culture of prawns as these ponds are maintained in the autotrophic range with a P/R ratio greater than one under high production and respiration rates. Previous authors found a higher P/R ratio for the main backwater system, but without fulfilling the latter condition. The present study confirms the need to give full recognition to both these parts of the backwater in planning detailed ecological studies in order to fully utilise the high aquaculture potential afforded by the Cochin Backwater.