Special collector and count method in a recirculating aquaculture system for calculation of feed conversion ratio in fish

Feed conversion ratio (FCR) is a measure of efficiency in converting feed into increased body mass. Traditionally used methods are time-consuming and labor intensive, and accuracy needs improvement. We describe a specially designed collector in a recirculating system that retains uneaten pelleted feed for determination of feed consumption. The collector and pellet count method were validated in 8-11 day tests with three fish species. FCRs were compared with those obtained by weighing feed. The count method increased accuracy of the FCR, streamlined the procedure after the uneaten pellets were collected, and results were not affected by inclusion of fecal matter. Mean FCR calculated by the count method (0.42 ± 0.05) was smaller than by the traditional weigh method (0.61 ± 0.19). The collector used with a recirculating aquaculture system and the count method is a promising technique for accurate determination of FCR in aquaculture research.