Recirculating aquaculture systems (RAS) represent a new and unique way to farm fish. Instead of the traditional open pond systems, the fish are reared at high densities in indoor tanks in a “controlled” environment using less water and land resources. Moreover, the systems are designed to improve waste management through biological filtration. However, reliance on conventional aerobic biofiltration processes for waste removal in RAS despite being an established procedure has its limitations. The biofilters require high oxygen concentration with relatively high aeration costs and the bacteria responsible for biofiltration takes long to recover in the event of system failure due to power outages. Besides, the bacteria have long start up and multiplication periods. Anaerobic biofilters processes (denitrification & anammox) make it possible to overcome the limitations of aerobic filters. The aim of our study was to determine the effects of aerobic and anaerobic biofiltration on the growth of Nile tilapia and water quality in a small-scale recirculating aquaculture system. The two biofilters did not show any variation in removing toxic ammonia and in maintaining water quality parameters within safe limits for growth and survival of Nile tilapia. The results suggest that anaerobic biofilters can substitute the conventional aerobic biofilters in recirculating aquaculture systems without significantly affecting fish growth parameters.
The Pan African Fish and Fisheries Association (PAFFA) is an international, quinquennial conference that brings together scientists from around the globe to share the growing body of scientific knowledge in the African continent. The 6th PAFFA conference was jointly organized by JRS Biodiversity Foundation, Malawian Government Fisheries Department, Lilongwe University of Agriculture and Natural Resources, United States Agency for International Development, The Deutsche Gesellschaft für Internationale Zusammenarbeit GmbH (GIZ), Food Agricultural Organization, World Fish, Mzuzu University, Southern African Development Cooperation secretariat, Malawi University of Science and Technology, and University of Malawi.
Zipporah Gichana is currently a PhD student at the Institute of Hydrobiology and Aquatic Ecosystem Management (IHG), University of Natural Resources and Life Sciences, Vienna (BOKU). She is doing her PhD study in the framework of the APPEAR project STRECAFISH. Her research is focused on effects of biological filters and plant species on water quality and fish performance in recirculating aquaculture and aquaponic systems in Kenya. She holds a Master degree in Fisheries and Aquatic Sciences from the University of Eldoret, Kenya, and post-graduate training certificates in Limnology and Wetland Ecosystem Management (UNESCO - Institute for Water Education, Netherlands) and Applied Limnology (BOKU). Before starting her doctoral study, Zipporah worked as a lecturer at the Department of Zoology, Jomo Kenyatta University of Agriculture and Technology.