Looking at the ingredient list I doubt that it's the "color enhancer" they use which earns it the "not for human consumption ticket...Typically the fish feed producing industry will use harmless cartenoids like beta-carotene to enhance fish color...mostly for things like farm raised salmon, koi etc...In the wild salmon (and other fish) consume a good deal of plant and algae based cartenoids through their consumption of small shell fish, invertebrates and to a degree, insects. It's what gives salmon meat it's typical orange color.

Salmon fed a crappy "farm diet" (remember that we've tried to turn this fish into our "chicken of the Sea") has a dull greyish unappetizing looking flesh that consumers don't like. So cartenoids are added to their feed so that processors don't have to artificially color the fish flesh (well, at least less artificial coloring can then be employed). Beta-carotene, the coloring agent in your "Top Fin" fish feed is harmless. However...

I would suspect that it's the Menadione Dimethylpyrimidinol Bisulfite that causes that brand to be labeled 'not fit for human consumption. Medione is "basically" a cheap, synthetic source of vitamin K...and it's sometimes called "vitamin K3". It's only used used in the West as a cheap source of vitamin K activity in some pet foods and animal feeds. In some countries with very large populations of poor people it has been/is used in human food items, but that is NOT allowed here in the United States...hence the label...

Will it kill you to eat those fish? Absolutely not. But I would switch feeds anyways and not use that "Top Fin" feed long term.

I'm a big fan of people making up their own minds based on good, or at least on available, information. So, I'm not telling you what to do or not do...That'll ultimately be up to you, but if you want my humble opinion...I'd still eat those fish, and switch feeds. 

Jeff-

There are many causes for one fish to go "belly up" so to speak.  Your question is a valid one and my opinion is that it is probably OK to have been eaten, but, let's look at how the fish may have died.  It could have been injured by other fish in the tank during feeding (especially with tilapia).  It could have been injured by running into something in the tank or even had a bad air bubble in its system.  We may never know what killed this one fish so chances are it would have been OK to eat.  You didn't say if other fish are showing signs of odd behavior or illness.  Now with that out of the way, I would not have eaten it, but it may be time to harvest some fish if they are that big, or at least thin down the population and put the bigger fish in another tank for future harvesting.

Jeff S said:

Last week I had a 2.25lb Tilapia laying on it's side in the tank. I gave it a couple of days to "recover" but it seemed to be getting weaker.  I decided to get rid of it. All the other fish seemed fine. Should I have eaten it? 

Thanks for weighing in Leo - I did enjoy your disclaimer.

Vlad, thanks for taking a closer look at the ingredients and finding the likely culprit. I will still eat these guys, but will switch the food ASAP. And I have learned my lesson...I will be reading labels very carefully from now on!