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The aquaculture industry has rapidly increased in response to the increasing world population, with the appreciation that aquaculture products are beneficial for human health and nutrition. Globally, aquaculture organisms are mainly divided into two divisions, aquatic animals (finfish, crustaceans, and molluscs) and aquatic plants (microalgae and seaweed). Worldwide aquaculture production has reached more than 82 million tonnes (MTs) in 2018 with more than 450 cultured species. The development of economical, environmentally friendly, and large-scale feasible technologies to produce aquaculture organisms (even aquatic animals and/or aquatic plants) is an essential need of the world. Some aquaculture technologies are related to aquatic animals or aquatic plants, as well as some technologies have an integrated system. This integration between aquatic plants and aquatic animals could be performed during early larvae rearing, on-growing and/or mass production. In the context of the blue revolution, the current review focuses on the generations of integration between aquatic plants and aquatic animals, such as live feeds, biomass concentrates, water conditioners “green water technique”, aqua-feed additives, co-culturing technologies, and integrated multi-trophic aquaculture (IMTA). This review could shed light on the benefit of aquatic animals and plant integration, which could lead future low-cost, highly efficient, and sustainable aquaculture industry projects.

The resistance of Channel Catfish Ictalurus punctatus, hybrid catfish (female Channel Catfish × male Blue Catfish I. furcatus [CB hybrids]), and Channel Catfish and hybrid catfish expressing the introduced cecropin B gene to Ichthyophthirius multifiliis infestation was investigated in two experiments. In experiment I, four fingerling groups were challenged, including cecropin‐transgenic Channel Catfish, cecropin‐transgenic CB hybrids, non‐transgenic Channel Catfish, and non‐transgenic CB hybrids. Non‐transgenic Channel Catfish survived for a shorter time than the other three groups. Survival rate was significantly different between non‐transgenic Channel Catfish and the other groups, which had similar survival rates. In experiment II, non‐transgenic CB hybrids had a less severe infestation than non‐transgenic Channel Catfish. Mortality rates were 62.4% and 40.2% for non‐transgenic Channel Catfish and CB hybrids, respectively. The mean survival time for non‐transgenic hybrids was significantly longer (>5 d) than that of non‐transgenic Channel Catfish. The results suggest that genetic enhancement of Ichthyophthirius resistance can be accomplished in Channel Catfish by either cecropin transgenesis or interspecific hybridization. In addition to survival rate, improving survival time is important because the extension of survival time provides greater opportunity to apply treatments to stop the protozoan infestation.

Our aim was to transplant blue catfish germ line stem cells into blastulae of triploid channel catfish embryos to produce interspecific xenogenic catfish. The morphological structure of the gonads of blue catfish (Ictalurus furcatus) in ~ 90- to 100-day-old juveniles, two-year-old juveniles, and mature adults was studied histologically. Both oogonia (12-15 μm, diameter with distinct nucleus 7-8 μm diameter) and spermatogonia (12-15 μm, with distinct nucleus 6-7.5 μm diameter) were found in all ages of fish. The percentage of germ line stem cells was higher in younger blue catfish of both sexes. After the testicular tissue was trypsinized, a discontinuous density gradient centrifugation was performed using 70, 45, and 35% Percoll to enrich the percentage of spermatogonial stem cells (SSCs). Four distinct cell bands were generated after the centrifugation. It was estimated that 50% of the total cells in the top band were type A spermatogonia (diameter 12-15 μm) and type B spermatogonia (diameter 10-11 μm). Germ cells were confirmed with expression of vasa. Blastula-stage embryos of channel catfish (I. punctatus) were injected with freshly dissociated blue catfish testicular germ cells as donor cells for transplantation. Seventeen days after the transplantation, 33.3% of the triploid channel catfish fry were determined to be xenogenic catfish. This transplantation technique was efficient, and these xenogenic channel catfish need to be grown to maturity to verify their reproductive capacity and to verify that for the first time SSCs injected into blastulae were able to migrate to the genital ridge and colonize. These results open the possibility of artificially producing xenogenic channel catfish males that can produce blue catfish sperm and mate with normal channel catfish females naturally. The progeny would be all C × B hybrid catfish, and the efficiency of hybrid catfish production could be improved tremendously in the catfish industry.

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