Genetically, it cannot be distinguished from the Yellowstone cutthroat trout,[4][2] and before the construction of dams, no physical barriers were between the ranges of the two subspecies in the Snake River drainage.
[4] The subspecies was scientifically named in 1995 in a popular book by columnist M. R. Montgomery, to honor the fisheries research of Dr. Robert J. Behnke, who had presented its (unnamed) description in 1992.
[5][4] While fine-spotted x rainbow trout crosses are observed in the South Fork of the Snake River in Idaho, they are infrequently encountered and appear to be hatchery hybrids.
In addition to their natural aversion to cross-breeding with other trout, fine-spotted cutthroats are unusual in their pursuit of a vertebrate diet, mainly other fish, but occasionally including small mammals.
While the fine-spotted cutthroats can be very selective feeders during a major hatch of aquatic invertebrates, they are not as focused as rainbow or brown trout, and can be diverted with small terrestrial imitations.