Use the free Betta Water Change Schedule below, right in your browser. No sign-up, no software to install, and nothing is sent to a server.
Betta fish are often sold as fish that need almost no care, but that myth harms more bettas than almost any other. A betta in a small unfiltered bowl lives in water that fouls fast, while a betta in a heated filtered tank with regular changes can live for years. This schedule sets how often and how much water to change from tank size and filter status.
Enter your tank volume in litres and whether the tank has a cycled filter. The tool gives a change interval in days and a percentage per change, plus the litres that percentage means for your tank. A filtered tank of twenty litres or more gets twenty five percent weekly, a smaller filtered tank gets twenty five percent every four days, and unfiltered tanks get fifty percent every two to three days.
Tank size drives the schedule because waste concentrates faster in less water. A single betta in five litres produces the same waste as a betta in forty litres, but the small tank has eight times less water to dilute it. That is why tiny bowls need changes every other day while a proper tank needs only a weekly change. If your tank is under ten litres, the kindest upgrade is a larger tank, not a stricter schedule.
A cycled filter changes the job of water changes completely. In a cycled tank, bacteria turn ammonia into nitrite and then nitrate, so changes mainly export nitrate and refresh minerals. In an unfiltered tank there are no bacteria to help, so ammonia builds directly and changes are the only thing standing between the fish and poisoning. Never treat a filtered schedule and an unfiltered schedule as interchangeable.
Cycling a filter takes patience, typically four to six weeks. During cycling, test ammonia and nitrite every two or three days, and change water whenever ammonia rises above zero, even if that breaks the schedule. A new filter is not a cycled filter just because it is running, and a betta added on day one of a new tank needs the unfiltered schedule until tests show the bacteria are established.
Dechlorination is not optional for bettas. Tap water chlorine burns gills and damages the delicate fin tissue that makes bettas so vulnerable to fin rot. Dose a dechlorinator for the new water volume, let treated water reach tank temperature, and add it gently so the betta is not blasted around the tank. A jug of treated water left beside the tank for an hour solves both temperature and chlorine in one step.
Temperature matching is especially important for bettas because they are tropical fish kept near twenty five to twenty seven degrees. Water even a few degrees cooler can shock a betta and trigger stress, clamped fins and disease. Keep a thermometer in the tank, warm new water to match, and never pour cold water directly onto the fish. A heater with a thermostat keeps the tank steady between changes.
Feeding and waste affect how well any schedule works. Bettas need only a few pellets once or twice a day, and uneaten food rots fast in a small tank. Remove any uneaten food within a few minutes, and fast the fish one day a week if you tend to overfeed. A betta that is slightly hungry is far healthier than a betta swimming in water fouled by yesterday dinner.
Watch the fish and the water together, because schedules are guides and tests are facts. A betta that is active, eating, building bubble nests and showing bright colour is thriving on its schedule. A betta that hides, refuses food, clamps its fins or gasps at the surface needs a water test at once, and usually a change at once, whatever the calendar says. Test kits are cheap, and they turn guessing into knowing.
Finally, build the schedule into a routine you will actually keep. Pick a fixed day for weekly changes, keep a bucket, siphon and dechlorinator together, and log each change on your phone. A schedule that is easy to follow beats a perfect schedule that is abandoned after two weeks. Your betta cannot change its own water, so your consistency is its clean water, and clean water is the foundation of everything else in betta care.
Versión en español: Cambios de agua para betta – Frecuencia y litros