What Bulb Do I Use To Bring Out Fishes Colour?

[deansplit]

I have a small wall tank with a T5 6w white florescent tube in it. It doesn't show the colours of the fish as well as you see in aquariums, and was under the impression it was a UV bulb that did that, and also killed the algae. So off I went and ordered an Arcadia fish UV UVC filter bulb, but noticed it was even dimmer than the white one! Once I contacted the seller (Ebay) then enlightened me (excuse the pun) that it is the wrong filter, belongs inside a pump and it'll burn the fish, let lone it's dangerous to human eyes!
 
So, what do I buy? I'm sure I've seen purple/UV lights in tanks??

 

[Byron]

The so-called "aquarium" or "plant" fluorescent tubes tend to be high in the red and blue wavelengths.  To varying degrees they can give the aquarium a ghoulish purplish hue which some people like (I don't for various reasons, but that is just personal opinion) and reds and blues on fish tend to be more predominate.  Other objects like decor and the substrate may turn strange colours with these, just be aware.
 
These are often suggested for planted tanks, but in fact they are much weaker in intensity that other "daylight" tubes.  But if you have no live plants and are only looking for colour highlighting, these will do it.
 
Byron.

 

[HarpyFishLover]

The so-called "aquarium" or "plant" fluorescent tubes tend to be high in the red and blue wavelengths.  To varying degrees they can give the aquarium a ghoulish purplish hue which some people like.

Oh, THAT'S the light at my LFS!

 

[StevenF]

Your eyes only see Reflected light and only  color of red, yellow, green, and blue.  Your eyes cannot see UV or infrared light.  So UV light is not going to affect the color of most fish.  However in some fish, coral, or plants UV is absorbed and then released in a color you can see.  So unless you have the genetically engineered Glow fish or coral  in your tank UV is not what you want.  
 
To get the best color you want a lamp that emits all the light  of blue, green, yellow, and red light.    Furthermore in most cases you want the light to as closely match the light from the sum.  So if you have a light that emits all the colors of light in the correct ratios of red to blue, blue to green and red to yellow you will see fish as they would appear in the wild.  
 
For lights there is a specification called color rendering index or CRI.  Lamps with a CRI of 100 will give you the best color.  A CRI of zero is the worst possible number.  So look for lamps with a CRI of as close to 100 as possible.  CRI is not related to color temperature or the Kelvin rating of a lamp.  The Kelvin rating describes the ratio of blue to yellow and red light.  The higher the kelvin number the more blue to light will be.  One lamp may have a high kelvin rating but a low CRI while another manufactures lamp may hav the same kelvin rating but a high CRI number.
 
LEDs emits all the colors of red to green but only emit one narrow color of blue.  LEDs typically are very good at showing reds, yellows, and greens.  Blues may not look as good.  In  the US Energy star labeled bulbs are required  to have a CRI of 80 or more.  Most are 80 to 90.  Those not labeled energy star may have a CRI of 70 to 90.  Some very expensive LED lamp are available with a CRI of 100.  Most shop don't carry these lamps.  LEDs offer the highest efficiency but generally they cost more.  they also tend to last longer than any other type of light.
 
Fluorescent bulbs can have a CRI fo 70 to 100.  Although most don't list the CRI number.  ZooMed make fluorescent bulbs for reptiles, coral, and fresh water aquariums.  Some are optimized for rebtiles, coral, plants, of just color.  Fluorescent lamps are resonably efficient at a resonable cost.
http/www.zoomed.com/
http/zoomed.com/Library/Care%20Sheet%20Documents/Aquatic_Lamp_Recommendation_Chart.jpg
 
Incandescent bulbs generally have very  good CRI although they are very inefficient and produce a lot of heat.

 

[NickAu]

 
To varying degrees they can give the aquarium a ghoulish purplish hue which some people like(I don't for various reasons, but that is just personal opinion)

I spent 100 bucks on a LED light just like that, Only to go out and spend another 90 on a different one for my 2 foot tank.