Kopiokau: The Double Espresso Blog

Would you believe that it is now possible to produce trout from salmon, a different species of fish?
Strange but true: although it does not seem impossible - salmon and trout are related members of mostly two common genera Salmo and Oncorhynchus. 
Japanese researchers have successfully implanted primitive sperm cells of the rainbow trout (Oncorhynchus mykiss) into the bodies of sterilized male and female Asian masu salmon (Onchorhynchus masu) embryos.  The sperm cells were primitive enough to evolve into eggs in the female embryos and sperm in the male embryos.  And voila! when the matured salmon did what comes naturally, out came trout!
This finding is considered of great importance in trying to replenish declining stocks of endangered species of fish. For full report see here.

See also Scientific American report.

Salmon-spawned Trout