To predict the possible effects of climate change on marine organisms and water quality, this study evaluated the long-term effects of pollution on Sparus aurata & Dicentrarchus labrax in Alexandria on the Mediterranean Sea and Suez on the Red Sea concerning their seasonal variation. The physicochemical factors pertaining to seasonal variation in mean temperatures at the Mediterranean and the Red Seas were documented. They ranged from 17.26 ‒25.73ºC with a mean value of 22.01±0.31 in Alexandria and from 17.35 ‒ 29.98 ºC with a mean value of 24.27 ±0.54 ºC in Suez. The collected water samples had mean concentrations of dissolved oxygen (DO) ranging from 3.94‒8.28 (6.77±0.42 mg/L) in Alexandria to 4.65‒9.38 (7.08±0.53 mg/L) in Suez. The oxidizable organic matter (OOM) mean varied between 5.40‒ 10.4 with a mean value of 8.10±0.76 mg/L in Alexandria and 5.74‒11.06 with a mean value of 8.77±0.84 mg/L in Suez. Mean salinity differed between 37.36 ‒ 39.62 with a mean value of 38.42±0.23 in Alexandria and 40.28 - 42.92 with a mean value of 41.63±0.28 at Suez. The mean pH values varied from 7.96 ‒ 8.57 with a mean value 8.30 ± 0.04 in Alexandria while ranging from 7.61 - 8.34 with a mean value 8.07±0.11 in Suez and thus indicating that the water was slightly alkaline. Temperature had a major impact on the liver tissue's catalase (CAT) and Glutathione S transferase (GST) activities. All values of CAT & GST activities in Suez were higher than in Alexandria. CAT activity in the Mediterranean Sea during summer showed lower values than in the Red Sea, which were 3.76 ± 0.08 & 4.18 ± 0.04 U/mg protein respectively. On the contrary, the activity of GST in Seabass Dicentrarchus labrax with gilt-head bream Sparus aurata were 120.18 ±1.37 & 123.75 ±1.28 U/mg protein respectively at the Red Sea. In comparison, the activity was lower in the Mediterranean Sea in the summer than in the Red Sea, which was 116.55 ±0.75 & 119.18 ±0.68 U/mg protein respectively.