Can a uv light in on or near a fish tank harm the fish?

UV lights are run as part of the filtration system, but not where it will shine on the fish. It kills parasites and viruses and there are a lot of mixed feelings about the use of it since it will kill beneficial bacteria floating in the water as well. It also only sterilizes the water that passes through it, and the free-floating harmfuls have a chance to reproduce/infect fish before getting pulled through. It is useful is you have a multi-tank system and you want to sterilize the water before it goes into the next tank.
only if they are fish that live on the bottom of the ocean.
Maybe it can harm but not for sure!
depends on the fish.

UV lights are used in tropical fish tanks to help keep the water clean.

"a high intensity electrically operated Ultraviolet (UV) bulb is located inside the unit's wet chamber. This UV bulb gives off Ultraviolet light (UV) wave emissions when lit. The bulb's operating emission range is within the Ultraviolet light (UV) wave spectrum at 253.7 nm of wavelength. This wavelength is such that when bacteria, protozoa, viruses, algae spores, or other single celled waterborne microorganisms in the incoming water flow are exposed to the light waves of the UV bulb or one second or more exposure time, the DNA of the microorganism is altered or disrupted, which controls and eradicates these unwanted contaminates and renders them harmless."

From a commercial companies website that I do not wish to name for advertisement reasons.
Not if the UV light is placed outside the tank as glass blocks UVA and UVB light.
Probably only really sensitive fish but I would check to make sure!
not with the fish but please be careful of your uv light
no it shouldnt hurt them

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