Title: Design and comparison of the performance of three recirculation systems for fingerling production

Three simple recirculation aquaculture systems (RAS) for fingerling production were designed and constructed and their performance compared. Design A was similar to RAS units used currently in Cameroon with a UV filter while design B was without the UV filter. Design C had a simple unit with an airlift pump instead of the mechanical pump used in systems A and B. Each system had three rearing tanks (24 L). The materials for construction were same in all the three designs and all systems had equal volume of water. Arctic char juveniles were stocked at 55 and fed with extruded feed (1.5mm) for 30 days. The final mean weight of char in all systems was similar (0.76-0.80g). The survival rate in design A and C was similar, 97% and 98% respectively, while the survival in system B was lowest (94%). Just after the termination of the experiment nearly all fish in system B died of unknown causes. The performance index (PI) showed that the best performance was from design A (PI=2.6) followed by design C (PI= 2.5) and lastly design B (PI=2.4). The water quality variables were similar in all systems, except the bacterial count was lowest and constant in system A, which included the UV filter, and highest and increasing in system B. The results showed that the UV filters are an important component of the RAS and should be included when systems are designed. System C, with the airlift pump, also performed well and could be an option for RAS systems in Cameroon, depending on their running cost, reliability and efficiency of gas exchange.