I was wondering why some fish have red eyes

[Magnum Man]

When I had fish 20 years ago, one of my favorites was a pair of angels that had red eyes… back then I called them my “stoned angels” there seems to be several species of fish, that this trait is pretty common… I looked it up, and came across this article…

Fish with red fluorescent eyes forage more efficiently under dim, blue-green light conditions

Natural red fluorescence is particularly conspicuous in the eyes of some small, benthic, predatory fishes. Fluorescence also increases in relative efficiency with increasing depth, which has generated speculation about its possible function as a “light ...

www.ncbi.nlm.nih.gov

Which in a nut shell indicates that it may help fish see their prey in deeper or shaded waters…
Curious if those familiar with species that have red eyes agree with that, looking at their natural habitats???

 

[GaryE]

Last summer in Gabon, we caught a red eyed lampeye not far from a blue eyed one a few streams away. They clearly belong to different groups within their Genus, with different fin shapes as well. The eye colour breeds true.

The habitats looked pretty well the same, but that was last year. What they were way back I can't guess. For all we know, the little rivers could have been very different when the eye colours evolved, and that could have been before humans did.

I've seen red of various tones in the eyes of a lot of fish, and I am convinced they can't smoke underwater. Cichlids from both Africa and South America may offer clues, because all the ones I've seen with red eyes came from rivers. The ancient forest canopies would have really limited light, where lakes wouldn't have.

We fished one stream under a canopy of leaves, and it was a dimly lit place, strangely beautiful but an adjustment.

It's sensible to ask why all tiny fish from rainforests don't have red eyes, if it's an advantage, but it doesn't work that way. It's interesting.

 

[Uberhoust]

Interesting article, I will have to read it better this evening. A couple of my angels have half red eyes, and I would swear if they are not happy it is not as bright.

 

[Uberhoust]

I've seen red of various tones in the eyes of a lot of fish, and I am convinced they can't smoke underwater

Edibles?

 

[GaryE]

I bought some assassin snails from a local breeder a couple of weeks ago, and when I went into the apartment, it smelled like I was passing the ventilation outlet of the weed factory that used to be at the end of my street (it's legal here). When I took the snails out of the baggie she'd put them in, there was weed floating on the surface.
Yes, I had turbocharged assassin snails, with the munchies.

 

[Oldspartan]

Edibles?

Water pipe

 

[TwoTankAmin]

Some fish have red eyes because they are albino.

Others have red eyes because they drank too much booze the night before.

 

[CaptainBarnicles]

Some fish have red eyes because they are albino.

Others have red eyes because they drank too much booze the night before.

I guess that's where "drinks like a fish" comes from

 

[MuddyWaters]

I am convinced they can't smoke underwater.

gummies man...gummies...

 

[GaryE]

This is not a great picture, but reflective eyes are hard to photograph. This is part of my shoal of Platopochilus sp Sousoube. It's a mix of wilds we caught this summer, and young from them. The red eyes are amazing, especially as the light goes down. You no longer see the fish, just red red eyes darting like ghosts.
The second shot is in normal lighting. I have LEDs that dim for the evening rather than snap on and off, and shot one is in the fade period.