There are several things that can be going on.
First, fish do change colors - when the lights are going down, they will take on their "pajama coloration" or literally their sleeping colors. They may also change colors when stressed or excited. If you suddenly turn different lights on or off, then you can stress fish and their color or pattern may change.
However, you have to remember what color is. Color is the reflection of particular wavelengths of light. So, green plants are green because they reflect green wavelengths.
When you get into the ocean, most wavelengths are absorbed very rapidly, within the first couple of meters. Blue, however, is not. Which is why there is a blue tinge.
But this has a major impact on coloration of fish. When you see a photograph of a reef without additional light, it is actually rather drab. But when you add a strobe - artificially add in the wavelengths - loads of colors appear.
With actinics, you basically have blue wavelengths available. So the fish looks very different in coloration..there simply are not many colors, or wavelengths of light available to reflect. When you add more wavelengths with your halides, then the color seems to "perk up" when in reality it may be nothing more than the physics of light.