clownfish can't synthesize beta carotene that is found in foods such as shrimp. I saw a study done by some students at FIT about certain foods in the industry to make the orange (natural color) in a clownfish come though. they had a "yellow" clownfish of all different ages. they found it was the type of feed that kept them from their natural color of orange. tetra flake was obviously the worst and i believe there was no change, cyclopeeze was the best and took the clownfish only 60 days to change, and gellybelly was a close second. formula one flake was third. i do not believe rods food was tested during this study. so if you want your clown to stay yellow, feed him foods without shrimp! keep in mind this study was done on ocellaris and percula.