Continous Light

I was recently doing some research on genetics in fish and stumbled across some very interesting information.

Although not genetically influenced this is still pretty amazing. It seems that while doing tests on some Angelfish it was found that those raised under continuous light (24Hr) did not produce the stripes that would otherwise be found.

A Sliver Angel was used as an example. Under 14 hours of light a day to produced the typical 3 black stripes. When raised under continuous light for the first few months the stripes never appeared or returned.

The same held true for Zebra Angels. With these however, after being raised in continuous light for many months, small black dots reappeared when the light was removed.

A few more examples were given and I found it all to be amazing that something like this could influence the outward appearance of a fish. I know that many people would commonly say that light/no light makes no difference to fish. While this may be true when it comes to behavior this is just one example where appearance can be changed permanently.

I wonder if anyone else has had this occur on other fish and under what circumstances. Have to love all these little things that just go completely unheard of!


REF. http://www.theangelfishsociety.org/articles/norton/dr_norton%286N%29.html

I can believe this Striking. I put those two Angel fish in my pond three months ago and at the time they were silver. They only get short morning sun and short afternoon sun in the pond. although I have yet to be able to catch them when I do see them they look to be almost all black. Same with the guppies. The females who are clear in color turn black in the pond and huge.

Yup that was exactly the type of thing I was thinking of. I am going to be looking up some more information regarding this when I get a chance.

That's really interesting... I wouldn't have ever guessed that something like that would permanently affect their markings! I assumed that those were genetic, like spots and such on horses, dogs, and cats. Who knew?! Thanks for sharing that!

I had read this too, very interesting. Actually considered trying it but never followed through.

This picture will show the difference in the guppies. The one in front was taken out of the pond. The one futher back was from a tank.

Light actually plays a big part in a fishies development.

Have you read Dr. Endler's findings on the coloration of streampool guppies? The guppies were found to change their spots and coloration almost instantly according to the environmental factors present in each of the various stream pools. Environmental factors included light, substrate, and which predators were present in the pools. Fascinating. Professor John Endler's paper on this subject is very famous and you ought to be able to find sections of it quoted on-line. I read most of it in the book The Beak of the Finch.

Here's another one from the pond that was clear when put in it.

That is really amazing haha. I know many fish have harder top halves when the bottom of the water is dark to help protect against flying predators and their bottoms would be white to help disguise from predators below.


I am thinking about keeping a batch of my next silvers in constant light and see if their stripes won't show up.