The short answer
For a trip of up to about a week, feed nothing before you go and let your fish coast. Healthy adult fish handle seven days without food easily, and an empty stomach is far less risky than the alternative — a well-meaning neighbour dumping in too much and fouling the tank. For longer trips, use a battery automatic feeder set to small portions.
Trips up to a week
Counter-intuitive but true: the safest holiday feeding plan for a short trip is no feeding at all. A brief fast won’t harm your fish, whereas leftover food rotting in the water spikes ammonia and can crash the whole tank. Feed normally right up to the day you leave, then simply switch off the lights on a timer as usual.
Longer trips
For a week or two away, an automatic feeder is the dependable option. Fill it with your normal flake or pellet, set it to drop a small portion once a day (or every other day), and test it for a few days before you travel so you know the dose is right. Pair it with a light timer and your tank runs itself.
Before any longer absence, set the tank up to be stable: do a water change, clean the filter, check the heater, and top up evaporation. A healthy, well-maintained tank drifts far less while you’re gone. See the maintenance schedule for a pre-trip checklist.
The bottom line
Short trip: fast the tank, it’s fine. Long trip: auto feeder plus timers. Either way, avoid overfeeding above all. For more on how long fish cope, see how long fish can go without food and can I leave my fish alone for a week. Explore feeders in the fish food hub.