Winter Saltwater Fish Care — Cold Weather Protection Guide

Sudden winter water temperature drops dramatically increase disease risk for marine fish, particularly white spot disease. Here's how to maintain stable water temperature.

Heater Capacity Calculation

Required wattage depends on room temperature.

• Room temperature around 15°C: Approximately 2W per liter (150W for a 60L tank)
• Room temperature around 20°C: Approximately 1.5W per liter (100W for a 60L tank)
• For rooms with unstable temperatures, choose generous capacity

Accurate Thermostat Settings

• Set temperature to 25°C as the baseline. The goal is stable maintenance within 24–26°C
• Install the thermostat temperature sensor in an area with water flow for accurate readings
• Regularly verify thermostat accuracy with a digital thermometer

White Spot Disease Risk and Prevention

Temperature swings of 2°C or more dramatically increase white spot disease risk.

• Always temperature-match water before adding during water changes
• Watch for nighttime room temperature drops. Water temperature drops when heating is turned off at night
• Foam board or insulating sheets around the tank buffer temperature changes

Winter Feeding Adjustment

• Don't stop feeding—reducing to 80–90% of normal is sufficient
• Reducing from twice to once daily can prevent digestive issues
• If water temperature is stable, major feeding reductions are unnecessary

Healthy Marine Fish from Buri-Choku

On Buri-Choku, you can purchase healthy marine fish directly from breeders. Winter care consultations are available directly from breeders, giving you confidence through the cold season.