Vacation: what do I do with my fish?

A few days without food is fine

It's common to worry about your fish when you're going away, but most of them do much better than you'd think. Fish are cold-blooded and use little energy, and in nature many of them go a long time between meals.

Healthy adult fish in a cycled tank can easily go four or five days without food, and many can manage longer. A short break does them no harm. What can actually go wrong while you're away is almost always that someone gives them too much food, not too little.

The exceptions are fry and very small fish, which need to eat more often, and fish that are already sick or thin.

Before you leave

The most important thing is that the tank is stable when you leave it:

• Do a water change a few days to a week before you leave, not the same day. That gives you time to see that everything is fine.
• Don't clean the filter right before. Do it a week or two ahead instead, so the bacteria have recovered.
• Don't add new fish in the last couple of weeks before your trip. A new fish can get sick or produce more waste than the bacteria can handle, and you won't notice in time.
• Test the water and check that ammonia and nitrite are 0.
• Check the equipment. Are the heater and filter working as they should? Is the light on a timer? A tank with the light on around the clock quickly gets algae. See Lighting: how long and how bright.
• Feed as usual until you leave, not extra on the last day.

Vacation feeder blocks

Vacation feeder blocks are lumps of food set in plaster or lime that are meant to dissolve slowly over several days. They sound handy, but they have many downsides:

• They make the water worse. Most of the block dissolves without being eaten and turns into waste, just like overfeeding.
• Many fish don't eat them.
• They can change the water's hardness and pH, since they dissolve in lime.

The Norwegian Food Safety Authority (Mattilsynet) advises against them because they can pollute the water. For a short trip, it's safer to skip them.

Automatic feeders

An automatic feeder drops a portion of dry food at set times. It can be useful when you're away for a long time, but:

• Test it at home first, ideally for a few weeks, and see how much it actually releases. Many give more than you'd think.
• The food can get damp and clump, so the feeder jams or releases everything at once.
• Set it to less than you'd give yourself. It's better for the fish to be a little hungry than for the water to go bad.

Someone to look after the tank

Mattilsynet writes that even if the tank can manage without care, a responsible person must check regularly that everything works. If you're away for more than a few days, or have fish that need frequent feeding, the same person can feed them. Make it easy for them:

• Split the food up in advance into small bags or a pill organizer with one portion per day. It's the surest way to avoid overfeeding. Well-meaning helpers almost always give too much.
• Ask them to feed every other day rather than every day, if your fish can handle it.
• Write a short note with your phone number, what to look out for, and what not to touch.
• Ask them to remove dead fish and check that the filter and heater are running.

It's rarely necessary for them to change water or test it. It's better for them to do too little than to do something wrong.

When you get home

Look over the fish and test the water. Feed a little less than usual for the first few days, and do a water change. If something looks wrong, Sick fish: how to spot it and what to do first is a good place to start.

Also read Feeding: less is more for more on how much your fish really need.