You’re eyeball to eyeball with a walleye surfperch. I love the yellow streak on the upper part of the iris. One of the ways we identify the walleye is by its large eye.
Honestly, the eye doesn’t seem that large when viewed on live specimens in the wild. When I encountered a large male I got the idea to measure the proportional size of the eye and compare it with that of a close relative, the silver surf perch. I measured the height and length of the eye and the head, then calculated the ratio. In a fish with a proportionally bigger eye, the eye:head ratio will be a larger number.  Here are the results. Length: walleye = .33; silver = .22. Height: walleye = .38; silver = .34. The walleye has a proportionally larger eye, especially in the length dimension. The field guides are correct!
theoutershores 
Eyes are amazing! This is a nice shot, too. Even on fish, eyes are wonderful to look at. I must admit, if I look at this pic too long, I just want this poor fish to BLINK, even though I know it can’t. So I blink instead. It helps a bit.
You seem a little surprised that the field guides are correct. Do you often find them to be factually inaccurate?
One minor question about the numbers: what’s the sample size? Did you measure one eye from each fishie, or both (is there a difference in relative sizes on individual fish? I wouldn’t expect there to be, but I haven’t had the opportunity/inclination to actually measure.)?
Hi Megmi, BLINK! The field guides are right most of the time, but they are covering a lot of ground, so they can be incomplete or even wrong at times. Love your sample size question, uh…I just measured one eye from each fish, so don’t bet the farm on those ratios.