can someone please help ? my angelfish s very sick , he is turning somersaults and swimming very erratically sometimes on his side and seems to have lost all sense of co-ordination , i have 2 other angels and many other various community fish which all appear fine , all water perameters are okay , i dont think this angel will last the night , can anyone tell me what this could be and or offer any advice for a cure ? thanks in anticipation !