Research Article: The effect of media biofilter and aquatic plant (Ceratophyllum demersum) on water quality of recirculating aquaculture systems, growth and survival rates of ornamental fishes

This study was conducted in order to compare the hornwort aquatic plant (Ceratophyllum demersum) with an artificial filter for purification in a recirculating aquaculture system (RAS). At first, the fluctuation of nitrogen components of the water reuse system equipped with artificial filtration was evaluated. Experiments were performed during three months. The hornwort aquatic plant was collected from Siadarvishan River and brought to the breeding and rearing system (JANAT Agriculture high school-Rasht). Subsequently, the plants were kept in river water for one month for adaptation. Initially, the plant wet biomass was weighted. For this purpose, 600 fishe specimens from the Cichlidae family (Oscar, Anjel, Burli and Zebra) provided from a local market were distributed between 12 aquarium tanks (160-liter capacity) in triplicate groups. Nitrogen component of water, such as ammonia (NH3), nitrite (NO2-) and nitrate (No3) were measured. Growth parameters and survival rate of fishe specimens at the end of the trial were evaluated. The results of this experiment indicated that nitrogen component when using hornwort aquatic plant as a biofilter not show better performance than the artificial filter treatment. The growth parameters performances when using the aquatic plant as biofilter in comparison with artificial filter declined.