I don't have the experience with green mandarins but I was able to get my scooter dragnet to eat prepared foods in a week by shutting off all my pumps so the water didn't move and spot feeding him with brine shrimp and cyclops shrimp. Now he eats anything I put in the tank and comes to the front of the tank when I feed. I have a hob
aqua clear 70 that I have a list on from a 2.5 gallon tank with nothing in it but chaeto and there are a lot of pods
building in it and my little scooter seems very happy and isn't skinny but he's not very big yet only about 1.5 inches.