Will my lighting hurt these fishes’ eyes?

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One PFK reader would like to know if his LED plant specialist lighting will cause his albino Kribs any problems.

Q) Should fish with a lack of pigment in their eyes, such as albinos, have lower lighting levels? I’d like a pair of albino Kribs but my tank is well planted and has LED plant specialist lighting. Is this going to cause my fish any problems?

STU GARDENER, VIA EMAIL

A) NEALE MONKS RESPONDS: As a rule, the colour pigments in land animals, and which are lacking in true albinos, are there, in part, to protect them against ultraviolet (UV) light. Things are a bit different for animals living underwater though, because UV penetration rapidly diminishes with depth, particularly when the water is murky, as is often the case in the tropics. Needless to say, even a thin layer of plant leaves will pretty much block any UV light.

While many surface dwelling fish species probably do need some protection against UV, there are obviously many other species that are more or less transparent, including numerous popular tropical fish species, which evidently get by just fi ne without any pigments that might block UV light.

The experimental evidence on how albinism affects fish is ambiguous. Experiments done with ricefish showed no significant difference in the survival of albino fish compared with normal ones when both were exposed to UV light. On the other hand, a similar experiment done with albino flounders demonstrated a higher rate of mortality compared with the normal kind.

Bear in mind that these experiments involved exposing the fish to deliberately high levels of UV-B light, something you’d be unlikely to do in a home aquarium. Similarly, while UV has been implicated as the cause of skin cancers (melanomas) in hybrid Xiphophorus livebearers, the experimenters used a particular crossbred variety precisely because it was prone to this particular type of problem.

Unless you’re using a lot of high output lights (more like the ones used in marine tanks than the average freshwater community) then lighting level isn’t going to be a major problem for your albino fi sh. The amount of UV light coming from the average fluorescent tube or LED lighting unit isn’t going to be enough to damage cells, even those without the benefit of protective pigments like melanin.

The bottom line, then, is that the goal has to be to provide the necessary lighting levels alongside options that allow any fish to find a suitably shady place to go if they want to.

If you’ve got bright lights for the sake of your plants, any decent thickets of vegetation should do the trick so far as your Kribs are concerned, and they will presumably have a couple of caves as well. Very few small tropical fish appreciate intense overhead lighting anyway, and it’s just good fishkeeping to provide shade as well as open spaces for swimming. So long as you don’t go crazy, there’s no particular reason to be concerned that your Kribs will be significantly more sensitive to your proposed lighting system than any of the other fish.

Did you know?

Albinism is caused by an absence of melanin, which gives colour to the skin. This lack of pigment also results in the eyes being pink or red, due to the blood vessels being visible. A condition known as leucism results in a loss of skin pigment, but doesn’t affect the colour of the eyes.