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I was in the petstore last week i heard him telling someone that hexagon tank can make a fish blind? Is it right

What??? Was there anything else he said? Maybe with somekind of light to a light-sensative fish. I don't know...

Chris

Under normal circumstances, no. The fish from my hex tank are just fine. Maybe if you use those underwater laser lights or something... Still I don't think acrylic or glass reflects enough to do anything.

yeah i was thinking laser lights also...

Chris

No, of course it isnt true, its possible that a strongly recurved or convex tank could cause damage to eyesight over the long term, especially since fish eyes are just that, very wide angle lenses. Lasers, or very bright led lights, blacklights, disease, flukes , and vitamin deficiency or abrasion will be the main causes of blindness in fish. For a hex tank to actually cause blindness via a prism effect in the water there would have to be sunlight hitting the tank in a direct beam, and no fishtank should be allowed to have that happen, if for no other reason than it overheats the tank and promotes algae.

Another fine example of petstore BS.

Your story is partially true. It is not a hex tank that blinds fish though it is a ROUND bowl (not the one with the two/three sides that are flat but the ones that are a compleate circle) Thats why they were banned in some countrys.

Inky

Ummmm... and how does a ROUND bowl blind fish?

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Before you criticize someone walk a mile in their shoes. That way you're a mile away and you have their shoes.

I've never heard of bowls causing problems. How do you measure blindness in fish anyway? They rely alot on smell and feeling vibrations. I've had a few blind fish(completley missing eyes so definitely blind) and they acted just like all the others.

I remember reading an article produced by a research team at cambridge years ago on the effects of housing on the eyesight of occupants from mesh cages to vivaria and fish bowls. I think the long and short of it was that the concave/convex nature of bowls caused difficulties with focusing and caused intense focused reflections and spectrum distortion and that these damaged the muscles that the animals used for focusing and as such they became very short sighted, and in some cases there was blindness caused by the complicity of focused beams of light from hoodlights and external daylight sources. This occured across the spectrum including mammals , fish, amphibians and reptiles. Its a bit like you wearing the wrong prescription glasses all the time. A lot of fish like arowanas and other surface feeders need to be given focal spots to prevent conditions such as drop-eye caused by the long term degredation of eye muscles. Whether you notice symptoms or not is kinda irrelevant, its just not a nice thing to happen for no good reason. Flat walled tanks and acrylic tanks cause the least distortion , and as such allow fish to use their excellent long distance vision with minimum impedance.Bowls create distortion, as indeed does water and heat, but unlike a bowl the distortion from the water itself is not constant and changes continuously, thusly causing the fish to readjust its vision.Obviously there are naturally short sighted fish that come from misty or dark waters , and for them there will be minimal if any damage , but clear water species, especially line-of -sight predators, will be affected.