Brazilian and German scientists have completed a collaborative project to sequence and analyze the whole genome of Arapaima gigas, a giant freshwater fish known in Brazil as pirarucu and elsewhere as arapaima or paiche. Its growth rate is the fastest among known freshwater fish species. Its natural distribution covers most of the Amazon River basin in Peru and Brazil.
The research led to discoveries that help determine sex at an early stage, facilitating the separation of female and male fry for sex-specific breeding and sale. It also paves the way for further studies relating to genetic improvement of the species.
The findings of the research, which was supported by FAPESP, are published in Scientific Reports.
The collaboration began in 2015, when Manfred Schartl, a geneticist at the University of Würzburg in Germany, was contacted by biologist Rafael Henrique Nóbrega and his then Ph.D. student Marcos Antonio de Oliveira. Oliveira has since earned his doctorate from São Paulo State University’s Aquaculture Center in Botucatu, Brazil.
Nóbrega, a professor at the university’s Bioscience Institute (IB-UNESP), proposed collaboration on research into the mechanisms of sex determination and differentiation in A. gigas.
“It’s the world’s largest freshwater fish and an iconic Amazon species with considerable economic value, so Schartl was surprised that its genome was unknown at the time and that genetic markers hadn’t been identified for sex determination,” Nóbrega told.