View Full Version : green barbs turning blue?
riffless
06-23-2003, 2:42 PM
has anyone seen this in green barbs? two of the three barbs I have are turning a blue-ish color where they used to be green... is this common... they live in a 30 gallon with three barilius pulchellus and a pleco... 7.2-7.4 ph, 0 ammonia... they don't appear to be sick or diseased, and haven't been acting funny at all, they're jsut changing color... they do live with 4 live plants, so I wonder if that doesn't change their shading...
wetmanNY
06-23-2003, 4:05 PM
That blue or green color is a "structural color" that comes from an interference pattern as light is refracted among crystals of guanine that lie above black melanophores in deeper skin layers. The effect is called the "Tindall effect" from the British physicist who first gave a satisfactory exolanation for it.
Fish have melanophores to give black and brown colors, and other pigments that produce red, orange and yellow. But there are no blue or green pigments in fishes.
Similar effects are seen in bird feathers (http://www.suite101.com/article.cfm/13515/64722) that are blue or green. Have you ever noticed the blue or green highlights on a black crow in sunlight?
riffless
06-23-2003, 7:01 PM
I kind of suspected that it might be the angle I was looking at the fish from, but there's one that is still a deep green, while the other two are really blue now... so by your explaination, this is simply a light/angle trick of the eye? thanks, I read the article you linked (and am a bit of a bird watcher myself, which made it that much more interesting)
mickey
06-24-2003, 6:57 PM
Originally posted by wetmanNY
That blue or green color is a "structural color" that comes from an interference pattern as light is refracted among crystals of guanine that lie above black melanophores in deeper skin layers. The effect is called the "Tindall effect" from the British physicist who first gave a satisfactory exolanation for it.
Fish have melanophores to give black and brown colors, and other pigments that produce red, orange and yellow. But there are no blue or green pigments in fishes.
Similar effects are seen in bird feathers (http://www.suite101.com/article.cfm/13515/64722) that are blue or green. Have you ever noticed the blue or green highlights on a black crow in sunlight?
Now thats what you call a brilliant and informative reply.
Cheers.