The applicability of dissolved air flotation (DAF) treatment to fish filleting wastewater from the harbour of Mar del Plata was evaluated. The experiments were planned by factorial design, the variables were pressure, coagulant and recycle, each at two levels (2(3) factorial design). The responses measured were the reduction in chemical oxygen demand (COD), reduction in total solids and reduction in protein content. The results indicate that the three factors significantly influence the performance of the treatment and that there exists a high degree of interaction between the factors studied. Within the experimental conditions investigated reductions of chemical oxygen demand (up to 74%), of total solids (up to 62%) and protein fish scales as flotation aids are shown, measuring the reduction in total solids.