For a 19-liter betta aquarium with just one beta fish and a filter, you should only need to do a full clean every 6 to 8 months. If your tank is planted with a good filter and a balanced ecosystem of “clean” tank companions, it can go years without cleaning. For a typical tank with plants, rocks, or other objects, you should clean it once a week. If there are betta fish but no plants and only one or two objects, you should clean it every two weeks.
To clean a fish tank without a siphon, you must first prepare the water, move the fish, remove the decorations from the tank, change the water, clean the substrate of the tank, and finally adjust everything back to its place. A 5 gallon tank should be cleaned weekly, while larger tanks such as 15 or 20 gallon tanks only need to be cleaned once or twice a month. It's difficult to get a fully self-sufficient betta tank because you would have to perfectly emulate natural conditions. To ensure your betta fish thrive in their home, you must keep their tanks clean.
When changing the water in your betta's tank, it's important to give them time to acclimate to the new conditions; you don't want your betta fish to die of shock. Nitrate is the end product of this nitrogen cycle and can often exceed safe levels for fish if the aquarium gets dirty, full of people, or if bettas are given too much food. If you don't think you can clean your tanks frequently enough, you can also opt for a tank with a filter or introduce an aquaponics system. It's difficult to give an ideal time frame for cleaning a betta tank depending on its size as it can become dirty within 24 hours due to bacterial proliferation.
To keep your tank clean and remove any accumulated debris, you should clean your betta fish tank as often as necessary. When it comes time for your betta fish to reproduce, it's easy to tell as the male will build a spectacular bubble nest to attract the female.
