There is no single safe fasting period for every aquarium fish. Species, size, age, health and usual diet matter. Do not assume that advice for healthy adults also applies to fry, underweight fish or specialist feeders.
This guide focuses on food and feeding checks. For room temperature, equipment, water changes and emergency access, use the summer aquarium travel checklist.
Choose the feeding plan before you leave
Keep a familiar, suitable diet and agree a schedule for the animals you actually keep. If their needs are uncertain, ask an experienced aquatic professional or aquatic veterinarian before changing the routine. Do not add a large meal to cover several days or assume every bottom-dweller can live on algae.
Option 1: measured portions for a sitter
Prepare clearly labelled portions for the agreed feeds and demonstrate how to use them. Include any different foods or feeding locations needed by particular residents. Ask the sitter to report missed meals or unusual behaviour, not to compensate with extra food.
The RSPCA's holiday feeding advice supports prepared meals and daily checks, including when an automatic feeder is used. Explain that checking fish and equipment is part of the visit, not an optional extra after feeding.
Option 2: a tested automatic feeder
Use a model compatible with the intended food and mounting position. Trial the actual portion size and schedule for several days while you are home. Confirm that food reaches the fish rather than the filter intake, and that quieter residents can feed too.
- Check the correct power source, battery condition where applicable, clock and feeding programme.
- Mount the unit securely and protect it from splashes as its manual requires.
- Keep the food dry and remove any clumped food according to the instructions.
- Keep designed ventilation openings clear; do not tape them over or add unapproved material to the hopper.
- Have a person confirm that the feeder actually dispenses as intended during your absence.
Ventilation can be part of the feeder's design: EHEIM describes an actively aerated food chamber for its standard autofeeder. Follow your own model's instructions rather than modifying it to match a generic holiday tip.
Do not introduce an untested feeding block
A product being labelled for holidays does not establish suitability for every aquarium. Check the exact food, instructions and livestock requirements. The RSPCA advises against holiday feeding blocks because uneaten food can pollute the water. Do not substitute a new block for a working, observed feeding routine at the last minute.
A short instruction card
Write down the food, amount, feeding times, where it goes, which fish to watch and who to contact. Add: “Do not double the next feed after a missed feed; contact me for instructions.” Leave a reference photo of the aquarium and tell the sitter how to report leftovers, breathing changes or a feeder fault.
After returning, observe the fish and check water quality before making changes. Resume the appropriate routine without a compensatory feast. If water conditions look questionable, use the aquarium test-kit guide rather than judging safety from clear water alone.