Utilization of Sludge from African Catfish (Clarias gariepinus) Recirculating Aquaculture Systems for Vermifiltration

Vermifiltration is a low-energy and low-cost option to reduce the environmental impact of aquaculture. A comparative study was performed for two different stocking densities epigeic worm Dendrobaena veneta (Michaelsen, 1890, Annelida: Oligochaeta), which were fed with sediment sludge from African catfish, Clarias gariepinus (Burchell, 1822), recirculation aquaculture systems (RAS). The intensive (I) extensive (E) stocked 15 10 g worm/L filter substrate, respectively, compared control (C) four weeks. total weight gain 9.4–13.5% 13.8–19.5% (E), low mortality rates 3.46–5.84% 3.57–5.19% (E). temperature inside vermifilters slightly higher than that in control, indicating favorable milieu microbial activity. worms supported pH buffering capacity systems, effluent reaching 7.10 ± 0.02 7.26 0.04 at end experiment while significantly (7.51 0.05). removal 68.02–98.84% (I), 71.85–98.67% 72.80–98.68% nitrogen bound (TNb); 82.77–96.64% 81.65–94.84% 77.79–94.74% organic carbon (TOC); 50.43–97.51% 50.89–96.84% 48.23–96.34% chemical oxygen demand (COD). By utilizing as feed, associated microbiota altered catfish sediments, removing loads, upgrading composition, reducing possible impacts.