Biwa Trout and Similar Species
Oncorhynchus masou rhodurus
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Open the appSeveral fish can be confused with Biwa Trout. Here are the key differences.
Species often confused with {name}
Masu Salmon (Cherry Salmon)
Oncorhynchus masou masou
Key differences: The anadromous form of Masu Salmon. While genetically very close, O. m. masou migrates to the ocean for its growth phase and returns to rivers to spawn. Biwa Trout (O. m. rhodurus) is entirely freshwater-resident. Morphologically, O. m. masou may exhibit more pronounced spotting and different coloration patterns depending on its life stage (e.g., ocean phase vs. river phase).
Amago Salmon
Oncorhynchus masou macrostomus
Key differences: Another subspecies of Masu Salmon, primarily found in western Japan. Amago typically has distinct red spots with blue halos on its flanks, a feature absent in Biwa Trout. Amago is also primarily a riverine resident, though some populations may exhibit anadromy.
Rainbow Trout
Oncorhynchus mykiss
Key differences: Rainbow Trout are not native to Japan but have been widely introduced. They typically have a prominent reddish or pinkish stripe along their lateral line and numerous small black spots over their entire body and fins, which are generally more extensive than those on Biwa Trout. Their caudal fin is also less deeply forked than that of the Biwa Trout.
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