"Color Changing" Fish

johnnypets · 01-22-2007, 05:27 PM

Has anyone ever noticed how dramatically the appearance of certain fish can change depending upon how much light is reflecting off the scales?

Below are two images of the same Green Tiger Barb fish in basically the same place with the only difference being that the first photograph was taken with flash and the second without. This is not a trick of the camera or an illusion, this is observable in "real life" as well.

If anyone else has any photos like this to share of other species, it might make for an interesting bit of information.

Tommy Gun · 01-23-2007, 02:24 AM

Cichlids are a great example of how fish can vary its coloration due to moods and or hierarchal position in a tank. For example, my big dominant male yellow lab is by far the brightest yellow fish in my tank and the lab that I would suspect is the least dominant is a very pale yellow in comparison. I also have one that it nearly white, but I believe that is probrably due to over breeding and genetics.

However, when talking about fish which can change colors rapidly and more so on purpose than the cichlid example, saltwater fish have to take the cake. Check out these pictures of my foxface:

^ This is its "normal" coloration during the day and while it is not feeling threatened at all by other fish in the tank (which is generally the case) and then its coloration at night time when it is 'sleeping' in a corner of my tank which it has apparently staked out as its bedroom area:

Just to add to this picture of my foxface a bit, it is also in what seems to be a comatose state when it is 'sleeping' and regardless of what I do, it will not move, probrably in an attemp to further bolster the appearance that it is not a fish but part of the live rock. Even if I get close to it with my long handled algae scraper, the most it will do is flare out its dorsal fins and get ready to defend itself with the venom.

My Mandarin Goby, which is a very popular fish due to its bright colors and odd color patterns will also camoflgage itself at night time to a good extreme in which it becomes nearly white and is very hard to locate it when there is live rock behind it. So far I havent gotten a very clear picture of it while it is in this extreme camoflage.

Great topic though. I bet this one could get pretty interesting. Tomorrow I am going to try to get some pictures of my new cichlids and I will hopefully get some which show the color variations between the dominant and less dominant fish of the same species.

johnnypets · 01-23-2007, 04:25 PM

Wow, that foxface does show a dramatic change!

I have found that the green tiger barbs don't change their color very much deliberately, except when very stressed, they will appear more dull. I believe the effect on the green tigers is due to the rirdescent reflective colors that reflect light.

As for fish that change colors at will, my favorite would have to be the Boesemani Rainbow Fish. When Boesemani Rainbows display their full colors I can't take my eyes off of them. Of course, the Boesemani Rainbow is one of my favorite fish!

Below are 3 photos of Boesemani Rainbow Fish. The first is a fish with average coloration. The second is beginning to color up. You can see the blue darkening and the yellow intensifying. The third is a fish fully colored - note the very intense colors and striking vertical and horizontal bars that appear!

Tommy Gun · 01-24-2007, 11:07 PM

I agree, that is a nice looking fish. I have never really looked into them much more than just information on care and husbandry, but I might think about getting some of them if I find the room someday. So, you are saying that they can change colors at will/whenever they want or need to, or is this just something that comes with age and maturity?

I know that foxface of mine is not really what you were getting at here, but I thought that it was still pretty cool how it can do this. I really cannot think of any other fish that I know of which would change colors rapidly or like a chameleon, but that would be awesome to find one and keep it around.

alexfevery · 01-25-2007, 01:02 AM

I have an octopus, and he changes colores if you look at him funny, in miliseconds, its amazing, he has a color for every mood,
but the frontosa ciclid i have, changes from white black and blue to all dark brown when ever i do a water change.

2leftfins · 01-25-2007, 01:30 AM

Interesting topic.

I was going to ask a question about my Tetras. There are a few who are very pale when I turn the tank lights on in the morning. I assumed it was just because of lack of light or something, but am wondering if it may be a health or stress issue.

The color returns shortly after the lights are on and they seem perfectly normal.

Cichlids4Ever · 01-25-2007, 07:57 AM

I don't see a health issue.
My tetras and barbs and a lot of other fish look pale in the morning when the light is first turned on.

This is absolutely normal.

Tommy Gun · 01-25-2007, 10:40 AM

I agree, probrably a normal thing and most likely it is from the lights just popping on in the morning. If you want to reduce this effect, you can put your lights on a timer so that one comes on before the other if in fact, you have two sets of lights. Otherwise, you can put a light in the room on a timer so that the tank does not go from being totally in the dark to fully illuminated. This is the trick I used to make sure that my cichlids do not run and hide for an hour every morning.

johnnypets · 01-25-2007, 06:56 PM

Tommy Gun, Yes, the rainbows can change color at will! They are really neat. There are certain things that will cause them to change color, mostly stress, competition, and mating time. Mine also get excited about feeding time and color up when they know they are about to get fed. Interestingly, when I have to net these fish, some will change to the dullest color they can while others will change to the brightest color. Also, dark gravel and low light encourage the fish to display brighter color.

That octopus sounds really fantastic! It must be very neat to have one! Do you have any pictures? It would be great to see some of his color variations!

As for the dull tetras, I think it is normal. When I have observed fish "sleeping" (that is, resting on the bottom and not moving during the night), they do not have bright colors and can look quite dull. I also believe that most fish are quite photosensitive. The other suggestions posted are good ones and I will only add this one: Fish remember when feeding time is if you feed them at regular times. So, you could try feeding them right when you turn the lights on. My fish are trained that way and no longer freak out when the lights come on, but rather gather at the top ready to devour whatever falls into the tank! The fish that would normally be dull when the lights come on start coloring up as soon as they detect me in the room and generally look stunning by the time I flip on the aquarium lights.

Tommy Gun · 01-26-2007, 12:29 AM

Quote:

I also believe that most fish are quite photosensitive.

I just read a bit of info about this same sort of thing and in it the author pointed out that while it cannot be proven scientifically that fish actually sleep or not, it is pretty well accepted that fish will either stop moving to rest or swim a constant pattern in the water so that they do not have to 'think' about what they are doing while they rest (that pertained to sharks because they cannot stop moving without dieing I think). Anyways, it was also pointed out that fish cannot diolate their pupils and so really bright lights are bad, for example a flash from a camera, as well as when it is dark and then instantly bright. The example was of scuba divers who go out at night and take pictures of 'sleeping' fish. I guess this disorients them quite a bit since obviously, in a lake or ocean, light is introduced gradually when the sun is rising and falling.