Feeding in Winter:
It is also possible to skip feeding your fish for more days at a time, especially since your fish should be eating less already (as previously stated). But before doing this, we highly suggest checking that the temperature in your tank will not be exceeding 72°F while you’re out or sleeping. We also recommend not changing your goldfish’s water before leaving for vacation, as the new incoming water may be colder and this can cause issues. Instead, we recommend doing a large water change before you go, and if you feel the need to change water more while away, try to siphon only a little dirty water out of the bottom of the tank rather than replace a substantial amount. This will still allow for fresh, oxygenated water to reach your fish.