Longitudinal distribution and niche partitioning phenomena have been extensively reported for streams containing two salmonid species but remain poorly understood for streams containing three or more salmonid species. Herein, we examined the abiotic environmental variables and population densities of fishes, including three salmonids, in 30 reaches of the Setose River, Hokkaido, Japan, across altitudes (120–450 m) and maximum...

Tetrodotoxin (TTX), known as pufferfish toxin, is a potent neurotoxin blocking sodium channels in muscle and nerve tissues. TTX has been detected in various taxa other than pufferfish, including marine polyclad flatworms, suggesting that pufferfish toxin accumulates in fish bodies via food webs. The composition of TTX and its analogs in the flatworm Planocera multitentaculata was identical to those in wild grass puffer Takifug...