Cross-eyed fishes: weird but true?

[Wyld-Fyre]

I'm currently cleaning out my fry tank/snailarium and have just noticed how dirty the glass is. That got me thinking.

(Trying very hard not to laugh here?! )

Do fishes have great 20/20 vision, because there is no doubt that my fishes will be troubled by seeing through dirty glass. Will they have poor eye-sight as a result of not being able to see clearly at the wider world?

(Snicker! )

If their eyesight is damaged, then please let me be the first to warn you of the dangers of not cleaning your glass!

(Snicker, Snicker! )

 

[Never2Bknown]

Fish do not have very good eyesight, due mainly to the general lack of light in the natural world of fish; sunlight cannot usually penetrate very far down in lakes and in oceans. Thus, they depend more on their highly developed sense of smell as well their lateral lines, which detect low-frequency vibrations in the water and determine their source. In fact, some fishes, such as blind cavefish, live without any sight whatsoever. It has been reported that one fish lost both eyes to Pop-eye disease, but still managed to live for a long time afterwards with little disability.

As to becoming cross-eyed, I do not believe this is possible; while mammals distort their pupils so as to see better, fish, due to the refractiive qualities of water, move their eyes in and out. THus, while we can become cross-eyed, I don't think that it is physically possible for fish.

When it comes to clear or cloudy glass, I wouldn't worry about it. I think we look into the aquariums more than the fish care to look out. In fact, there is actually species of fish for which cloudy glass is beneficial. I don't remember its name, but if put into an aquarium of clear glass, this fish would continually batter itself against the sides in an attempt to get out so much that it would end up breaking its jaws and face. (That has to be one of the world's dumbest fishes!)

Still, I must say that you do have point.