Selecting the right die to produce any kind of animal feed pellets becomes one of the difficulties is facing the pellet mill factories. Most of aquatic feed pellet mill factories use dies with holes diameter of 3.5mm, while the market has different dies with the same holes diameter, but with different total thickness and different L/D ratio, because the dies hole diameter of 3.5 mm not just use for fish feed pellets as well as for poultry feed, and rabbits feed pellets. The main experiments were carried out in one of aquatic feed Pellet mill plant to determine the optimum fish feed ring die design specifications and die holes dimensions. The parameters under investigation were three kinds of dies with different total thickness and L/D ratio, four different formula retention time in pre conditioner and three different formula temperature in pre-conditioner. The obtained results recommended the use of die2 (45.5mm total thickness with 1:13 L/D ratio) with die entry diameter of 4.25mm without relief, and optimum pre conditioner processing were 90s retention time, and 85C^o formula temperature, the obtained results of this parameters were 7.553Mg/h pellet mill production rate and 7.277Mg/h final production rate after cooling and sifting by decrease in productivity of  3.97%, 137 A motor current , 9.36 kW.h/Mg energy requirement of pellet mill, 101.12C^o operating die temperature in the range of safe die temperature. The measured quality produced aquatic feed pellets were 903.20 kg/m³ pellets bulk density, 95.69% pellets durability, and 70.67 % and 33.24% pellets water stability after 30 and 60 minutes sinking in water. The study recommended use the previous mentioned die specification with any pellet mill capacity with change in die eternal diameter