Going on Holiday? How to Keep Your Fish Alive While Away

Leaving your aquarium unattended is one of the biggest sources of anxiety for fishkeepers. Whether it is a long weekend trip to Johor Bahru, a week in Bali or a three-week holiday in Europe, the same question comes up: will my fish survive?

The good news is that healthy adult fish are far more resilient than most people think. With proper preparation, your tank can run safely for a week or more without any intervention. The bad news is that well-meaning but uninformed helpers often cause more damage than doing nothing at all.

This aquarium vacation guide covers everything from pre-trip preparation to what to tell (and not tell) your fish sitter.

Pre-Trip Preparation

The work you do before leaving is far more important than any gadget or fish sitter. A well-prepared tank is a stable tank.

One Week Before Departure

Perform a large water change: 30-50% instead of your usual 20-30%. Start your trip with the cleanest water possible
Clean your filter: Rinse media in old tank water to ensure good flow throughout your absence. You do not want a clogged filter while you are away
Check all equipment: Verify that the filter, heater (if used), lights and any other devices are functioning properly. Replace anything that looks questionable
Trim plants: Remove dead leaves and trim overgrown stems. Decaying plant matter produces ammonia
Test water parameters: Confirm that ammonia and nitrite are at 0 ppm and nitrate is at a reasonable level. Fix any issues before you leave, not after you return

The Day Before Departure

Feed fish normally — do not overfeed “to stock them up” (this does not work and only pollutes the water)
Top up the water level, especially for open-top rimless tanks
Set all timers for lights and CO2 (if applicable)
Unplug any non-essential equipment that could malfunction (decorative lights, UV sterilisers)
If using an auto feeder, do a final test run

Advice by Duration

Duration	Feeding	Maintenance	Monitoring
Weekend (2-3 days)	Do nothing. Healthy fish fast easily for 2-3 days	None needed	None needed
1 week	Optional: fast the entire week, or use an auto feeder	None needed if preparation was done	Optional: ask someone to glance at the tank once
2 weeks	Auto feeder recommended	None needed for most setups	Ask someone to check the tank and top up water once
3+ weeks	Auto feeder essential	Fish sitter should do a small water change at week 2	Weekly check-ins by a trusted person

Weekend Trips (2-3 Days)

Do absolutely nothing special. Feed your fish the morning you leave and the evening you return. Healthy adult tropical fish can fast for 3 days without any issues. Do not leave extra food, do not ask anyone to feed them, do not worry.

One Week Away

Most adult fish can fast for a full week and be perfectly fine. They will be hungry when you return, but they will not be harmed. If this makes you uncomfortable, use a tested auto feeder set to dispense a small amount once daily.

The key risk for a one-week absence is not starvation — it is equipment failure. A filter that stops, a heater that malfunctions, or a CO2 system that dumps its entire cylinder can cause far more damage than a week without food. Having someone glance at the tank once during the week provides valuable peace of mind.

Two Weeks Away

An auto feeder becomes more important for extended trips. Set it to dispense a conservative amount once daily. Have someone check the tank at least once during your absence to confirm equipment is running, the auto feeder is dispensing properly, and the water level has not dropped dramatically.

Three Weeks or More

For trips longer than two weeks, you need a fish sitter — someone who visits at least once a week to check equipment, top up water and confirm the auto feeder is working. Ideally, they should do a small water change (15-20%) at the two-week mark using pre-treated water that you prepare before leaving.

Auto Feeder Setup

Automatic feeders are simple devices that dispense a set amount of dry food at scheduled intervals. They are reliable and affordable, but they need to be set up and tested before you leave — not on the morning of your departure.

Choosing an Auto Feeder

Drum-style feeders (like the Eheim Everyday or ISTA auto feeder) are the most common and reliable. They rotate to drop food through an opening
Price range: $25-$60 SGD
Use high-quality pellets or granules — flake food can jam the mechanism or clump in humidity
Avoid feeders with very large compartments — they encourage overfeeding

Testing Procedure

Install the feeder on your tank at least 3-5 days before departure
Load it with the food you plan to use
Set the timer and portion size to the smallest setting
Watch it dispense for several cycles — is the amount appropriate? Does all the food fall into the water?
Adjust the opening size if needed. Smaller is always better than larger
Check that humidity does not cause the food to clump and block the opening (a common issue in Singapore’s climate)

Tip: Place a small packet of silica gel desiccant inside the feeder’s food compartment to absorb moisture and prevent clumping.

What to Tell Your Fish Sitter

The most important instruction for any fish sitter is this: less is more.

More fish have been killed by well-meaning helpers who overfed than by any other vacation-related cause. A non-fishkeeper who is told to “feed the fish” will almost certainly give too much food, too often. They feel guilty giving just a tiny pinch, so they add more. Repeat this for a week and you return to cloudy, ammonia-laden water and sick fish.

Instructions to Give Your Fish Sitter

Pre-portion the food: Prepare individual daily portions in small labelled bags or a pill organiser. Each portion should be slightly less than your normal feeding amount. This removes all guesswork
One portion per day, maximum: Make this very clear. No extra “because they looked hungry”
Do not adjust any equipment: No turning dials, unplugging things or “fixing” anything unless there is an obvious emergency (like water on the floor)
Top up water if needed: Leave a container of pre-treated water with clear instructions: “pour this into the tank if the water level drops below this line”
Contact you if something looks wrong: Provide your phone number and a brief description of what “wrong” looks like (equipment not running, water on the floor, dead fish)

If you do not have a trusted fish sitter, an auto feeder on its own is often the safer option for trips of two weeks or less.

Timers and Automation

Your lights and CO2 should always be on timers, but this is especially critical when you are away. Manual switching is not an option if nobody is home.

Light timer: Set for your normal photoperiod (6-8 hours). Do not extend it while you are away
CO2 timer: On 1 hour before lights, off 1 hour before lights off. If you are nervous about CO2 running unsupervised, you can turn off the CO2 entirely for the duration of your trip. Your plants may suffer slightly but they will survive
Air pump timer (if used): Set to run during the dark period for oxygenation

Smart plugs are particularly useful for holidays — you can check the status of your equipment remotely and turn devices on or off from your phone if needed. See our aquarium timer guide for detailed recommendations.

Evaporation and ATO in Singapore

Singapore’s heat (28-32 degrees Celsius) and the air conditioning cycle in most HDB flats and condos can cause significant evaporation, particularly from open-top rimless tanks. Over two weeks, the water level can drop considerably, concentrating minerals and potentially exposing equipment.

Solutions

Auto Top-Off (ATO) system: An ATO uses a float switch or optical sensor to detect when the water level drops, then pumps fresh water from a reservoir into the tank. This is the most reliable solution for extended absences. Basic ATO systems cost $40-$100 SGD
Large water reservoir: If you do not have an ATO, fill a large container with treated water and ask your fish sitter to top up the tank during their visits
Reduce evaporation: Place a glass or acrylic lid over rimless tanks. This dramatically reduces water loss and also prevents fish from jumping out
Lower the water temperature: Turn off any cooling fans before you leave if using an ATO — the fan increases evaporation rate significantly

If your ATO reservoir runs dry while you are away, the ATO simply stops working — it does not cause any damage. Size your reservoir for the expected duration plus a safety margin.

What NOT to Do

Do Not Use Vacation Feeder Blocks

Those white, chalky “weekend feeder” or “holiday feeder” blocks are one of the worst products in the aquarium hobby. They dissolve slowly, releasing a mixture of low-quality food and binding agents (usually plaster of Paris) into the water. The result is cloudy water, elevated phosphates, ammonia spikes and often a tank full of dead or stressed fish when you return.

An auto feeder or simple fasting is infinitely safer than these blocks.

Do Not Overfeed Before Leaving

Fish cannot “store” food for later. Giving them a huge meal before your trip only produces more waste in the tank, which decomposes and degrades water quality while you are away. Feed normally the day before you leave.

Do Not Ask an Uninstructed Friend to “Look After” the Tank

Without clear, specific instructions (and pre-portioned food), a non-fishkeeper will almost always overfeed. “Just feed them a pinch” means different things to different people. Pre-portion the food or use an auto feeder.

Do Not Make Major Changes Before Leaving

Do not add new fish, change the substrate, rearrange hardscape or start a new medication regime in the days before a trip. Any change can destabilise the tank, and you will not be there to respond if something goes wrong.

Frequently Asked Questions

Can fish really survive a week without food?

Yes. Healthy adult tropical fish can fast for 7-10 days without any lasting harm. In the wild, fish do not eat every day. Their metabolisms are adapted to periods of scarcity. Fry, very young fish and some species with high metabolisms (such as very small nano fish) are exceptions and should have access to food via an auto feeder.

What if my power goes out while I am away?

Short power outages (a few hours) are not a problem — the water retains its temperature and the bacteria in your filter survive for several hours without flow. Longer outages (12+ hours) can cause the filter bacteria to die from lack of oxygen, potentially causing a mini-cycle when power returns. There is not much you can do about this remotely, but having a battery-powered air pump as backup provides some insurance.

Should I leave the lights off while I am away?

No. Keep the lights on their normal timer schedule. Plants need consistent light, and a sudden extended dark period can trigger algae problems when lights resume. Fish also benefit from a consistent day/night cycle for their biological rhythms. Timers handle this automatically.

I am going away for a month. Should I board my fish?

For very long absences (a month or more), you have a few options: hire a professional fish sitter, ask an experienced fishkeeping friend to check in weekly, or engage a professional aquarium maintenance service like Gensou to care for your tank on a schedule. This is the safest approach for extended trips.

Heading away and want peace of mind? Gensou offers professional aquarium maintenance services that cover feeding, water changes and equipment checks while you travel. Contact us at 5 Everton Park to arrange holiday care for your tank before your next trip.

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Going on Holiday? How to Keep Your Fish Alive While Away