Freshwater snails draw attention for being a cheap resource of proteins, fatty acids, vitamins, and minerals in eastern and north-eastern India, as well as in south-east Asia. They are harvested from water bodies to serve the local economically impoverished people or sold as a commodity in local fish markets. Owing to the growing demand, the unregulated harvest of the snails may push their population to decline drastically at the local level. The snails sold in markets are segregated based on size to attract the best price, which may bias the catch towards more suitable sizes. The catches from markets and water bodies were analyzed simultaneously for the maximum sustainable yield (MSY) of snails, providing future guidelines for sustainable harvesting. The catch per unit effort (CPUE) has been used as a novel proposed equation to calculate the MSY. The equation used in this article is MSY = CPUE_Market / CPUE_Field. The size-wise variability (measured through the diversity H') represented through 

the abundance of various shell length classes affected the total catch of the snails. The demand-wise segregation at markets biases the catch, as sizes differ between markets and water bodies. The present analysis provides the basis of guidelines for sustainable harvesting, though it requires further research using a novel concept of sustainable yield or CPUE and deducing newer methods for the calculation of sustainable harvesting.