The chemicals in the fish flakes could be harmful to the monitor,but it's hard to say, you would have to have a couple test groups set up along with a control group that's not getting any fish flakes plus a second control group with fish flakes that don't enhance the colour of the animal. you should start with a small group of 10 in each group for the initial test and then for the second test you should have a large number of animals (like 100 in each group). other then the fishflakes the diets and enviroments should be exactly the same. Photos should be taken every day so you can see the changes and also show them to an unbiased group of people.
sounds expensive doesn't it?