This is a one year old tank fully cycled. 0 ammonia 0 nitrite >10 Nitrate. 30% water change per week, temperature set to 18 degree celsius. Tank is 60 liter and only has 8 White Clouds in it. Fish has developed a bump on side which looks like pimple. Fish is active and eating fine but having problem staying above in water. I have also notice a white spot on its tail. Other fish in tank has no symptom. Please let me know if it going to be contagious. I have raised the temperature to 24. Please provide guidance, Thanks in advance.