Effect of AZOLLA weed on water quality in ponds at Ssenya fish farm

Abstract

In extensive and sub-intensive fish farming systems aquatic, macrophytes Azollahighly depended on as major or supplemental feeds for fish due to its protein content. In ponds however in fern results into water quality complications. To know the effect of free floating Azolla fern on water quality, a study was carried out in ponds at Ssenya fish farm for three weeks to link the Azolla mat with water physio-chemistry and effect of fertilizer on the biomass gain. The Azolla fern was planted in three ponds (100-140m2), two ponds fertilized with DAP and NPK respectively and in one ponds no fertilizer. In pond size of (110-140m2) the fern was already set and in two ponds. In the last three ponds measure (100-130m2) with control treatment. The dissolved oxygen decreased with increasing Azolla cover between 2-3 weeks, PH was alkaline throughout the experiment ranging between (7.77-7.47), temperature and transparence decreased with increasing Azolla cover. The higher difference in turbidity observed in treatment with Azolla established in comparison to the other treatments (p≤0.05). The Azolla biomass gain did not respond to the fertilizers applied in all treatments and has no significant difference in dry biomass (p≤0.05). Although there was variation, all parameters were optimal for biological process of the aquatic organisms.