They have to be trained to eat surface / non moving foods. I have two breeding groups of acf ,wild type and albino. The wildtypes were given floating pellets when they were young as part of their diet and will happily eat them. The albinos were introduced to floating pellets as adults and never really figured out they were food, if they were starved long enough they would probably figure it out but I haven't got the heart to do it. Persistance is probably the key, just keep trying, do yours hand feed ? If so try that, this species will readily take food from you, especially the females.