Aquarium care on holiday: do’s, don’ts, and how to prepare

How long can fish go without you?

Healthy adult fish in a well-maintained tank can typically go 3–7 days without feeding. Some hardy species manage longer. The real limits are: (1) hunger and stress, (2) water quality drift, and (3) equipment failure. A week away is usually fine if you prepare. Two weeks needs a plan. Longer than that and you need help — a fish sitter or someone who can at least check and feed.

Do: prepare before you go

• Big water change: Do a larger-than-usual water change (e.g. 40–50%) a day or two before you leave. Start with the cleanest possible water.
• Test and log: Check ammonia, nitrite, nitrate, and pH. Fix any issues before you go. Use a tank log or app like App-aquatic so you know your baseline.
• Clean the filter: Rinse media in old tank water (not tap) a week before departure. Don’t do it the day you leave — you might disrupt the cycle.
• Trim plants: Remove dead leaves and excess growth. Decaying matter uses oxygen and adds ammonia.
• Check equipment: Heater, filter, and lights. Replace worn parts. A timer for lights keeps the day/night cycle consistent.

Don’t: overfeed before you go

One of the biggest mistakes is “extra food so they won’t starve.” Uneaten food rots, spikes ammonia, and can crash the tank. Fish can go days without food. A single large feed the morning you leave is worse than skipping a day. If you’re gone less than a week, many tanks are fine with no feeding at all.

Automatic feeders: pros and cons

Automatic feeders dispense pellets on a timer. They work for short trips (up to about two weeks) if set correctly. Pros: No need for a sitter; consistent small portions. Cons: They can jam, overfeed, or run empty. Test the feeder for several days before you leave. Use the smallest portion setting. Place it where it won’t get wet or blocked. Battery backup helps if the power flickers.

Fish sitters: what they need to know

If someone is feeding your fish, keep it simple. Pre-portion food in daily bags or containers. Write clear instructions: how much, how often (usually once daily or every other day), and what to do if the filter stops or the heater fails. Leave your number and a backup contact. Warn them: less is more. Overfeeding is the number-one sitter mistake. A maintenance schedule or app reminder can help you prep a checklist for them.

Water changes while you’re away

For a week away, a pre-trip water change is usually enough. For two weeks or more, a sitter may need to do a change. Show them how: temperature match, dechlorinate, siphon from the bottom. Keep it simple — one change mid-trip is often sufficient. If no one can do it, ensure your tank is understocked and your filter is strong. See bioload and water parameters for context.

Emergency backup

Leave a contact who can respond if the sitter has a problem. Consider a smart plug or camera so you can check the tank remotely. If the heater fails in winter or the filter stops, someone needs to act. A written emergency plan (who to call, what to do) reduces panic.

Quick takeaways

• Do: big water change before leaving, test water, clean filter ahead of time, check equipment.
• Don’t: overfeed. Fish can go 3–7 days without food. Extra food causes ammonia spikes.
• Automatic feeders: test first, use small portions. Fish sitters: pre-portion food, stress “less is more.”