I've had this red tail shar for a little over a year now and he is in a African cichlid tank. Over the last few weeks has started to nibble on the sides of one on my cichlids (a star sapphire). The cichlid doesn't react much but after a bit might swim away a bit. His slime coat is starting to look a little bit whitened and he is acting a little most docile then normal. Is there any way I can stop or prevent this rainbow shark from doing it. Any help is greatly appreciated, Thank you.