Blue Trout - There is much less written information on the blue trout than either the golden rainbow or the palomino. There are numerous citations in the scientific literature and several mentions of them being stocked around the US. Several articles seem to indicate that the blue trout originated in France. There seems to be no genetic evidence the the blue trout is anything but a rainbow trout (Oncorhynchus mykiss).
A Blue Variant in the Rainbow Trout, Oncorhynchus mykiss Walbaum article in Journal of Heredity.
The Blue trout appears to have been originally developed" in France. Genetically, it is a rainbow trout. It is a color variation similar to the Golden rainbow trout and the Palomino trout.