For pellets, when comparing the ingredients, Dianichi is garbage compared to
Omega One Super Color Cichlid Pellets.
Unfortunately, NLS' list starts with "Typical Ingredients"<--- which sounds like garbage too.
What. It's white fish meal, most use fish meal. It's super processed. If you think they're sitting there wood smoking salmon to dump into $3.99 a bottle Petco Omega 1 fish food, you're probably incorrect. Dianichi
Ultima has very simiar ingredients, but has half the fat and more protein. Not that that's always necessarily a good thing...
Dianichi uses calcium montmorillonite clay for a bonding agent. This has been proven to "nuetralize metabolic toxins," but only by acting as a laxative. Dianichi argues that this equates into a more easily digestable food. I don't know about that, it could just be the high garlic content. I just know that the food has a "oily run-off" like NLS, which supposedly is a sign of the omega-3 content. Also, I've used all of them - and although Dianichi is pricey, the fish freaking love it. If they are getting ANY dianichi at all ,they will turn their noses up at the other food until I offer up more of the good stuff.
I'm not the only one to notice this. This
link from cichlid forum shows Dianichi products being ranked the highest repetitively down the board. If you read the other user reviews you'll notice others that have made the same observation.
Here goes a LONG discussion on this forum debating whether Dianichi or NLS was better - full of outrageous claims, fanboys, and your-momma jokes.
http://www.monsterfishkeepers.com/forums/showthread.php?214702-Dainichi-vs-NLS-Let-s-have-a-real-discussion-on-which-is-best!
As far as the OP's original question regarding color... I don't think any of them make a difference to be honest. There was an ongoing joke about the before-after pictures that one of the sites had of a bunch of fish who were given their product. The fish looked much better afterwards, but they also had black backgrounds, black substrate, and noticeably different lighting : P.
All this being said, I have two huge buckets of NLS Thera-A in my fish room right now, sitting there smelling horrible. I like it a lot, just prefer Dianichi because the fish seem to like it better. But fat kids love cake and turn their noses up at broccoli - so, again. Who knows.