This study aimed at determining the scale efficiency in tambaqui production in earth ponds developed in the metropolitan region of Manaus-AM.Eleven fish farms were analyzed and were sampled data regarding its characteristics, productive data, disbursement, infrastructure value and production value, in order to calculate the total operational cost and profitability indexes.For the DEA was applied the VRS/BCC (variable return of scale) Scissors model with input orientation, using three inputs (total operational cost, feed value, and depreciation, all in BRL($) per kilo) and one output (annual gross revenue, in BRL($) per hectare).The study showed that 80% of the fish farms (DMUs) had increasing returns to scale, with scale efficiencies lower than 65%, affected by lack of profitability, low technical and marketing knowledge, high production cost (R$ 4.
50 kg-1 can opener ) and low average sales price (lower than R$ 5.00 kg-1).