When I was growing out my domestic discus fry I wondered about the muscle development between wild and domestic discus. I found a lot of studies on this with commercial hatcheries for trout, salmon, and other fish. These studies were for food producing hatcheries.
I concluded, right or wrong, I needed to provide all the advantages I could for my fish. The amino acid that seemed to make the biggest difference is L-Lysine. I acquired a bottle of 500 mg tablets from Spring Valley Vitamin Company. Seeing that I did not make my own food I rationalized that it might be possible to add it to the tank water. I reasoned that the flake food would have to soak up some of the amino acid before it was eaten.
I experimented with the amount of tablets to add to my 65 gal Tank. I started with four 500 mg at a water change. The next water change I increased to 6 tablets. The discus did not like this amount so I settled on 4 tablets for all future water changes.
Since this was not a scientific experiment I did not have any control fish. When the fish were good size I discontinued the L-Lysine. Below is a picture of my Fire Red discus fish. You will notice distinct lines between the different muscle groups.
Did I contribute to this muscle development? There is no way to know I am sorry to say. The information I read states that L-Lysine helps in fish food until the protein intake reaches 40 percent then it does not help.
http://benthamopen.com/tofishsj/article ... ISHSJ.pdf; http://www.sciencedirect.com/science/ar ... 8614001690