Water Temperature: A sudden change in water temperature during the water change can cause stress to the fish, making them jumpy. Bettas are sensitive to temperature changes, and rapid temperature fluctuations can be uncomfortable or even dangerous for them. Ensure the new water is the same temperature as the old water, or close to it, before adding the fish.
Water pH: Similarly, a significant change in water pH can also stress your betta fish and make them jumpy. Bettas thrive in slightly acidic to neutral water, and drastic shifts in pH levels can irritate their gills and cause them to exhibit jumpy behavior. Make sure to check the pH of the new water before adding the betta fish and adjust it if necessary to match the ideal range.
Chlorine and Chloramine: Untreated tap water often contains chlorine and chloramine, which can be toxic to fish. These chemicals can cause damage to the Betta's gills, making it difficult for them to breathe, which in turn can lead to erratic and jumpy behavior. Use a water conditioner to remove chlorine and chloramine before adding fresh water to your Betta's tank.
Startle Response: Betta fish have sensitive hearing, and loud or sudden noises during water changes can startle them and cause them to jump. Try to keep the area around the tank quiet during the water change and avoid making sudden movements that may spook the fish.
Reduced Oxygen Levels: A sudden drop in oxygen levels after a water change can also stress your betta fish and make them jumpy. During the water-changing process, it's possible for some oxygen to be lost. It's a good idea to aerate the newly added water before pouring it into the tank. This helps improve the water's oxygen content and reduces stress on the fish.
By understanding these factors and taking steps to minimize stress during a water change, you can reduce the chances of your Betta fish becoming jumpy or exhibiting erratic behavior.