الفهرس 
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Abstract
Computer models are useful tools for analyzing water treatment units and fish metabolic response effects on overall system performance. The main objective of this work is to develope a model able to predict required heat to be added or removed from water tank, dissolved oxygen consumption and ammonia production for recirculating aquaculture system (RAS). The model was developed on python program and a stand-alone graphic interface user (GUI) was produced with the given name of “RAS designer and operation assistant”. The model can predict precisely the heat energy required to be added or removed to maintain the water temperature at optimum water temperature to guarantee fish welfare and productivity. It can also predict the required hourly dissolved oxygen addition and ammonia removing water to make water quality in the optimum range for Nile tilapia. The model was validated by comparing predicted by actual values. The predicted temperature of the water in the tank by the model ranged from 21.96 ºC to 33.26 ºC with an average of 27.92 ºC ± 1.34 ºC. The actual temperature of the water in the tank ranged from 22.20ºC to 30.90ºC with an average of 28.41 ºC ± 1.16 ºC. The actual oxygen consumption through fish respiration ranged from 197.42 to 484.97 mg o2 kg-1 hr-1 with average of 339.42± 83.11 mg o2 kg-1 hr-1 while, the predicted ranged from 176.42 to 457.56 mg o2 kg-1 hr-1 with average of 345.42± 86.79 mg o2 kg-1 hr-1 . The actual ammonia production ranged from 10.56 to 55.99 mg kg-1 hr-1 with average of 30.96 ± 12.45 mg kg-1 hr-1 while, the predicted ranged from 9.90 to 48.61 mg kg-1 hr-1 with average of 32.24± 12.44 mg kg-1 hr-1 . The actual average fish weight ranged from 4 to 122.79 g with average of 51.44 ± 35.90 g while, the predicted ranged from 4 to 135.86 g with average of 48.99± 38.49 g. The results proved that the model is reliable and valid to predict water tank temperature, the heat energy to be added or removed of water tank, total oxygen consumption, ammonia production, and the average fish weight concerning Nile tilapia raising in RAS.