Review of progress on fish breeding and seed production using Recirculating Aquaculture System

Fish seed is one of the primary input materials for the large-scale production in aquaculture industry. In this review, a systematic summary was firstly made on the artificial fish breeding, hatchery, and larval rearing using Recirculating Aquaculture System (RAS). It is much easier to keep the environment much more convenient for the parent fish to mate and spawn in the RAS, compared with traditional. Specifically, the flounder, grouper, and butterfish can successfully lay spawn in the RAS. Among them, the previous studies reported the culture density of 0.01-4.5 kg/m3, system recirculation rate of 9-76%/h, and water discharged 0.7-3%/day. In terms of the fish eggs hatching, three kinds of incubator were mainly used for the different kind of eggs. Mcdonald-type hatching jar was used for the trout, sturgeon, and seabass, all of which eggs were suspended in water. California-type incubation troughs and vertical incubators were mainly used for the salmon and catfish, of which eggs were be stationary. Similar to the Mcdonald-type hatching jar, the funnel type incubators were used for the fresh water fish, such as the big head, grass, and koi carp. Furthermore, the different requirements of the system to grow out have been summarized to evaluate the influence of the live feed, microorganism, tank size, and light condition on the fish larval rearing. Secondly, the overview has been provided for the fish breeding and seed production in China. The current large-scale artificial fish breeding and seed production were practiced either in the outdoor ponds, net cages or the flow through various systems. Most of the seed production facilities were outdated, where the control of water quality was depended only on the climate and water resources. More importantly, the production efficiency and quality of fish seed were much lower and unstable at present, leading to the less development of aquaculture. Therefore, it is very necessary to upgrade the fish breeding and seed production technology. Recirculating aquaculture can be a promising kind of land-based industrialized aquaculture, due mainly to the high production, high efficiency, strong reproducibility, and environment friendly. Because of the high controllable water quality, recirculating aquaculture can fully meet the harsh requirements for the fish breeding and seed production. Hence, a plenty of practices on the fish breeding and seed production using RAS have been carried out with the different species all over the world. Thirdly, three research fields can be developed to promote the practice of RAS in the fish breeding and seed production in the future. 1) It is essential for the biological response of parent fish, eggs, and larval to the RAS environment stressors in the system design and seed production. 2) The control technology of environment and water quality can be developed in the scientific system configuration for different fish species. 3) The corresponding intelligent equipment can also developed during this time, such as, the screening for the parent fish using the computer vision, automatic counting for the eggs and larval, as well as the smart feeder for the live food.