I am not completely sure what this is asking but I believe it would be. That the evidence would be that the fish would be getting less oxygen hence causing noticeable breathing problems (probably best spotted by looking at the lungs).
Like, where 4 canyons are located at? Alright then...
Grand Canyon - Arizona
Palo Duro Canyon - Texas
Bryce Canyon - Utah
Three Gorges - China
Lake Michigan is <span>the great lakes in the u.s. does not share a border with canada</span>