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Nile tilapia do not achieve the desired productivity in the semi-desert regions of Mexico, because of their temperature variations. Temperature needs to be regulated to obtain commercial weights in 6 months, as stated by governmental agencies. With the use of greenhouses it is not possible to maintain all year round the optimum water for tilapia production, thus the temperature effect needs to be considered. A comparison was performed between two different semi-arid environmental temperatures. Fingerlings were stocked (60 days) by triplicate inside a greenhouse. Water, greenhouse and environmental temperatures were measured. Fish were weighed at the end. The weekly average values were compared graphically. External temperatures were of 20.5 +/- 6.7 (ET = 20.5) and 16.9 +/- 8.4 degrees C (ET = 17) respectively. ET = 20.5 degrees C showed a more stable water (26.8 +/- 1.3 degrees C) and greenhouse temperatures (24.4 +/- 4.4 degrees C) while ET = 17 degrees C had a greater variation of water (22 +/- 3.3 degrees C) and greenhouse (18.7 +/- 5.5 degrees C) temperatures. Tilapia under ET = 20.5 degrees C achieved a better weight of 22.23 +/- 1.85 g whit a tendency for bigger weights while Tilapia under ET= 17 degrees C achieved a more uneven weight of 16.21 +/- 3.30 with a tendency for smaller fish. The temperature and growth variation will have to be considered when planning a tilapia production project to obtain the desired weights. Tilapia under greenhouse in semi-arid regions of Mexico, without any other technology, will only be feasible, according to the plans proposed by the government, during the warmer period of the year.