I have been trying to get my freshwater teacup off of blood worms which he has been eating since time of purchase (8 months approx). I have been trying to feed him tilapia. Krill has been offered to him too. I may try and get some market shrimp tomorrow. So far it has been three weeks. he looks and acts normal but still will not accept the tilapia. Is it ok for them to go this long without food? Any ideas?