intensity of coloration in Opae Ula

[Kiko]

I have a growing colony of about 100-150 Opae. There is a range of color patterns in this population. Most have red "saddles" Only a few are all red. Many are very pale. Is it common to have that much variation of coloration? Do they need sunlight in order to trigger their pigment intensity (like humans getting a tan)? I did seem to get more coloration when I began feeding them spirulina powder, but it might be just a confirmation bias on my part.

[Mustafa]

Although coloration can depend on many factors, including "mood" of animals, diet definitely plays a role. My reddest animals are in tanks where there is plenty of "naturally" occurring algae and other biofilm around. Although I don't use spirulina, it may help with coloration as it has lots of canthaxanthin. Food with beta carotene or astaxanthin will probably help, too. Just keep in mind that these guys don't need much food at all and that feeding too much is actually detrimental.