The study was carried out  at  Faculty of Agriculture, Ain Shams University to assess the effect of two of algae species (Arthrospira platensis and Nannochloropsis gaditana) on growth performance of monosex  tilapia fish (Oreochromis niloticus), fish were fed on a basal diet supplemented with 0,3,5,7% of each algae. To perform seven experimental treatments were assigned in three replicates each. The experiment was designated as follows:  (T1) control (without algae), (T2) basal diet supplemented with 3% spirulina (spiru 3), (T3) basal diet supplemented with 5% spirulina (spiru 5), (T4) basal diet supplemented with 7% spirulina (spiru 7), (T5) basal diet supplemented with 3% Nannochloropsis (nanno 3), (T6) basal diet supplemented with 5% Nannochloropsis (nanno 5) and (T7) basal diet supplemented with 7% Nannochloropsis  (nanno 7). Experimental tanks were a part of closed recirculating system, where almost constant environmental conditions were kept throughout the experimental period. Twenty-one quadrate fiber glass tanks with 108-liter water capacity were stocked with 15 fish per tank. The individual initial body weight (2.7 g) was recorded at the beginning of the experiment. All fish in each tank was weighed every two weeks during the whole experimental period. The fish were fed the experimental diet for 95 days Results indicated that nanno 5 treatment had higher significant trend (P<0.05) final body weight (FBW), average weight  gain (AWG) and average daily gain (ADG) compared with the other experimental treatments. The best specific growth rate (SGR), feed conversion ratio (FCR) and feed efficiency ratio (FER) were found in nanno 7. Also, it was observed that spiru 7 have a high significant difference (P<0.05) in protein efficiency ratio (PER) and protein productive value (PPV). On the other hand, the results showed that the lowest AWG, ADG and (FER) appeared in spiru 7%. No mortality in nanno7 and spiru 7. Finally, using of nano 5% or spiru 7% enhance growth performance and feeding in tilapia fish.

This study was carried out to evaluate the efficiency of mixed algal cultures for wastewater treatment. Free and alginate-immobilized forms of mixed algal culture were used. The highest removal percentages of biological oxygen demand (BOD) were 86.4% and 71.2 % after 32hrs and 48 hrs. in case of free and immobilized cells, respectively. Moreover, the highest values of chemical oxygen demand (COD) removal were 83.74% and 59.71% after 32hrs and 48 hrs for free and immobilized cells, respectively. Treatment with free cells showed removal values for total dissolved salts (TDS), phosphorus and NH3-N were 20.5%, 34.6% and 43.8% respectively after 32 hours. While in case of immobilized cells the highest removal values 18.4%, 34% and 58.5%, for TDS, Phosphorus and NH3-N, respectively were recorded after 48 hrs. Generally, concentration of heavy metals decreased due to treatment with algal free and immobilized cells. As a result of treatment with algal free and immobilized cells, 100% and 95.9% of Cu wastewater content was removed after 8 hrs and 48 hrs, respectively. Moreover, 96.2% and 98.1% of Fe was removed after 32 and 48 hours due to application of free and immobilized cells, respectively. As a result of inoculation with the mixed algal cultures in free cells 99.4% of Mn and 84.2% of Zn content were removed after 32 hours. Whereas, 98.6% of Pb content was removed after only 8 hrs. In case of using the immobilized cells the highest removal percentages of the three heavy metals recorded after 48 hours as follow 97.8% of Mn, 89.0% of Pb and 97.37% of Zn. Accordingly, treatment of wastewater with mixed algal free or immobilized cells is a fruitful method to produce an effluent of high quality to be used for irrigation. Whereas, the algal free cells were found to be more efficient than the immobilized ones.