# Effects of blacklight on fish



## Silverreng (Jan 4, 2009)

Hey guys, I have a fully cycled and well balanced 55g. tank that I am planning to soon turn into a species only for Metriaclima sp. 'Dolphin' Manda and I was hoping to add blacklights for a realy awsome effect. But my husband brought up an interesting point last night, will this have a negative effect on the fish? Anyone?


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## Hoggy Boss (Oct 4, 2006)

I think lighting is mostly for the owners benifit. The lighting shouldn't effect the fish in anyway.


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## Silverreng (Jan 4, 2009)

Awsome!! Thanks.


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## Number6 (Mar 13, 2003)

I have never used blacklight above a fish tank as I was told by a reputable source that it could easily cause blindness after prolonged exposure.


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## Silverreng (Jan 4, 2009)

Blindness to the fish? How would aprox. 1 hr. about four times a week effect things, is this amount of exposure 'prolonged'?


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## Number6 (Mar 13, 2003)

black light throws out Ultra Violet light... http://en.wikipedia.org/wiki/Black_light

I do not know how much exposure would be unhealthy, nor do I know that it WILL cause blindness in fish. Like I said... I won't try it as I have been advised against it.

What I do know is that many fish DO see in UV wavelengths and that this is an adaptation to living in deeper water. With that in mind, I could see that prolonged exposure to a bright source close to them might be able to burn out their retina and if that's true, then deep water species would be affected faster than shallow water species.

It may be that this sensitivity to UV light does not translate into blindness when a black light is used over the tank and that the person was simply trying to warn against a "possible" issue they are hypothesizing. I've never looked into it... mostly as I think a black light over fish is a dumb idea, but that's just my opinion on the topic.

I've tried to pass along as much info as I know... hope it helps! :thumb:


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## Joea (May 25, 2004)

This topic has come up a few times over the years and in most cases, the answer is in two parts:

1. Blacklights emit very low levels of UVA light which, even in a more powerful form, is relatively harmless (UVB and UVC light is far more detrimental).

2. Blacklights don't produce the effects you're hoping for or are expecting. They don't intensify the colours on the fish. Most often they unnaturally illuminate things like substrate and particles floating in the water. The fish are often hard to see.


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## Silverreng (Jan 4, 2009)

Thank you for your responses.


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