They fast from time to time... once my silver fasted for 6 weeks... keep trying different things ..take it back out if he does not eat it.. he will eventually turn around.. if he does not after a long period there are other things you can do.. but that is after all else fails..meantime do water changes.. maybe add a little aquarium salt.. follow directions for amount.. salt relieves stress... if he is having any... of course depending on tank mates ,... make sure salt is safe for them...and maybe even add a little garlic oil which enhances appetite...
