Effect of tank color on fish

[PasoFish89]

I came across some research showing higher cortisol levels in tomato clowns being reared in white background tanks. I instantly thought back to some advice I read/saw/heard somewhere saying to paint the back and bottom of a QT or hospital tank white to make things easier to see in regards to the fish. It didn't really sound like it would be easier to examine feces etc in QT with a white bottom so I used and still use blue bottoms and backs. Anyway, this research was based on one species for a limited period of time, so I wonder if it would translate to other species and other ages. I don't have the means to test this but it would be interesting to see the results. I could be misremembering the advice on QT tank color, but I would avoid it out of caution I suppose.

 

[Mr. Mojo Rising]

I've met a few fish breeders ,they all seem to paint the bottoms of their breeder tanks black, they swear it is less stressful for the fish and increases survival rate in the fry. Some of them even paint 3 sides of the tank and just leave one side open for viewing.

So there does seem to be something to it...

 

[ISpeakForTheSeas]

I instantly thought back to some advice I read/saw/heard somewhere saying to paint the back and bottom of a QT or hospital tank white to make things easier to see in regards to the fish. It didn't really sound like it would be easier to examine feces etc in QT with a white bottom so I used and still use blue bottoms and backs.

Yeah, you're probably right to be wary of that advice; generally speaking, a black background would offer higher contrast that would make it easier to see issues (which is why darkfield microscopes are generally better for seeing fine details than typical lightfield ones). I don't know how well that contrast would work with black fish though.

With regards to the stress on different fish species, I'd guess the white background would be more stressful for most fish - at least if they don't have enough proper hiding places in the tank with them. A couple of thoughts come to my mind on the matter, namely the fact that white reflects more light and that fish tend to hide in caves/cave-like nooks and crannies. In my mind, a darker background would make the fish feel more like they're in a cave or other safe space, and a lighter background would make them feel more exposed/visible to predators. Additionally, it might just seem really bright/reflective to them with a white background.

That's just my speculation though.

 

[exnisstech]

I'll admit I have no idea what cortisol levels are but I alway black out the bottom, back, and ends of my QT tanks and do not use bright white pvc. I've believe that it's less stressful on the fish. I have had fish that would try to hide in corners rather than hide inside white pvc. When I pulled the white pvc and put dark pieces in the would hide in them.

 

[PasoFish89]

I'll admit I have no idea what cortisol levels are but I alway black out the bottom, back, and ends of my QT tanks and do not use bright white pvc. I've believe that it's less stressful on the fish. I have had fish that would try to hide in corners rather than hide inside white pvc. When I pulled the white pvc and put dark pieces in the would hide in them.

Cortisol is the main stress hormone humans/animals produce. I’m gonna try black and see what happens!