Ive had a bala shark for almost 2 years now it was large (12") when I bought it, came with the 55 gallon tank I bought. Up until the past 2 weeks it has been feeding fine on flake and pellet food. About 2 weeks ago it began ignoring the food and has been eating live crickets dropped in the tank for my african butterfly. Is this abnormal and does it pose any danger to the bala?