As winter approaches, the water temperature will decrease. Many biological processes in fish are dependent on the water temperature, and resistance to diseases is one of the major challenges faced by outdoor fish.
What you can do during this time of the year is to:
1. dose your pond with vitamin C on a weekly basis (1-10mg/L),
2. make sure you are giving your fish the best fish foods and
3. check your water quality is optimal (pH 6.5-7.5, alkalinity 4-6 dKH, ammonia 0mg/L, nitrite 0mg/L and nitrate <50mg/L).
4. If you have introduced new fish, aquatic plants or shared pond equipment from a friend, it would be worthwhile to get your fish vet-checked to make sure you have not introduced any nasty diseases. It’s easier to treat fish while the weather is still warm, and their immune system is strong, than during the cold winter months.