Looking for advice, recently bought myself a male betta for the past 3weeks I have noticed he has a couple of white spots on his fin, so on the safe side I turned his heater up to 30 but the spots disappear & come back? He is eating well active & no clamped fins just these spots on his fins. He's in a 3 gallon filtered tank with heater & live plants ammonia 0 nitrate 0 nitrate 5. Any help would be great.