Serrasalmid and pimelodid fish hybrids represent important advances for aquaculture in Brazil, but they also constitute serious genetic risks to cultivated and natural populations. Serrasalmid hybrids (‘tambacu’, ‘tambatinga’ and ‘patinga’) result from crosses between Colossoma macropomum, Piaractus mesopotamicus and Piaractus brachypomus. Pimelodid hybrids (‘ponto e vírgula’, ‘cachandiá’ and ‘cachapira’) arise from crosses between Pseudoplatystoma corruscans, Pseudoplatystoma reticulatum, Phractocephalus hemioliopterus and Leiarius marmoratus. The problems associated with hybrids mainly result from inappropriate use because these animals are reproductively compatible with their parental species. This review shows that monitoring of fish hybrids using genetic techniques is necessary for their sustainable development in aquaculture. The genetic technologies used to identify fish hybrids include cytogenetic methods, which are considered to be low cost, and polymerase chain reaction‐based molecular markers, which are associated with high throughput. Therefore, both types of genetic methodologies should be applied in monitoring programs aimed at brood stock management, wild stocks, the trade of hybrid juveniles and processed fish products in markets. Moreover, physical and genetic confinement of hybrids in aquaculture operations will be necessary to avoid the problems posed by these animals. The expected result of these measures will be the production of genetically improved animals by fish farms, allowing the sector to develop further and offering high‐quality animal protein.
Herein, we have developed molecular markers for nuclear genes to use in multiplex-PCR and PCR-RFLP, with the goal of characterising hybrid lines derived from crosses between pintado Pseudoplatystoma corruscans and cachara P. reticulatum. These markers, together with others described previously, were used to perform molecular identification analyses as genetic subsidies for Brazilian aquaculture. These analyses were performed due to the problems of high mortality in the offspring reported by the aquaculturist. From a total of 16 broodstock samples, 13 were genetically identified as hybrids; surprisingly, nine of these hybrids were found to be post-F1 lineages. These data show that the fertility of these animals can seriously affect the cultivated stocks, thus causing financial damage in this aquaculture system. The establishment of PCR-RFLP and multiplex-PCR as molecular techniques allows for both the correct management of these animals and the routine monitoring of production and trade of fish hybrids in aquaculture. Consequently, such tools will enable a sustainable development in the aquaculture industry.
The importance of genetic evaluations in aquaculture programmes has been increased significantly not only to improve effectiveness of hatchery production but also to maintain genetic diversity. In the present study, wild and captive populations of a commercially important neotropical freshwater fish, Brycon cephalus (Amazonian matrincha˜), were analyzed in order to evaluate the levels of genetic diversity in a breeding programme at a Brazilian research institute of tropical fish. Random Amplified Polymorphic DNA fingerprinting was used to access the genetic variability of a wild stock from the Amazon River and of three captive stocks that correspond to consecutive generations from the fishery culture. Although farmed stocks showed considerably lower genetic variation than the wild population, a significantly higher level of polymorphism was detected in the third hatchery generation. The results seem to reflect a common breeding practice on several hatchery fish programmes that use a small number of parents as broodstocks, obtaining reproductive success with few non-identified mating couples. The obtained data were useful for discussing suitable strategies for the genetic management and biodiversity conservation of this species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.