I'll take your word Moose but I've caught hundreds of pike and seen red fin tips but never on the belly like that. Then again not every fish Timid caught in that video had it either.
The 36" fish I caught the other week in the NSR fought well and I was using walleye tackle so the fight was even more extended because of that and she had red fin tips but her belly was pale white. Then again the river had good current where I fished and is well oxygenated. Maybe it was the water temperature or oxygen content of the lake like you say. Timid mentioned it was really weedy there so maybe the low O2 was causing the hard fighters to light up like Rudolf when they got exhausted. Blood pushing to the skin in a high fat area like their belly definitely would cause a reddening of the skin. And it would look kind of like capillaries under the skin rather than lesions like Spank described.
Rewatching the video I think you're right and maybe I'm just not used to fishing lakes or rivers with low O2 levels so I've never noticed it.
Weird how geography can effect your perception of life & everything involved in so many ways.
Would love for a biologist to chime in just for peace of mind, though.
