Betta tanks can get cloudy for several reasons, including overfeeding, algae blooms and bacterial blooms.
Overfeeding is the easiest to check off the list. Your fish only needs a small pinch of food or about three pellets per day. If you are giving him more than that, you may be starting a cascade that leads to a cloudy tank. After a water change, give him a day of fasting, and then get him back on track with a feeding schedule.
Overfeeding and excess waste can also lead to algae and bacterial blooms. Algae blooms can occur when nitrogen levels from decaying materials rise in your tank, giving the algae a food supply they can thrive on.
Excess sunlight can also cause an algae bloom, so make sure not to place your betta tank in the sun. Algae are like plants, and anything that makes a plant grow will encourage algae growth.
Bacterial blooms often occur after water changes, and again excess waste can be to blame. Healthy bacteria are good, but when their numbers grow rapidly, it can cloud the water. They will balance out over time, and adding biological booster in this situation will only exacerbate the situation.
You can reduce the chances of a bacterial bloom by making sure you don’t remove a huge section of the bacterial population when you perform a water change. Perform a partial water change on tanks with filters (25-30%) and do not remove all of the filter elements at one time if you can help it.
Basic tank maintenance goes a long way when it comes to reducing the chances of cloudy water. Performing regular partial water changes, vacuuming the gravel to remove excess waste, and following a smart feeding schedule are three big things you can do to keep the water clean and healthy for your betta.