Betta fish need oxygen for survival. Signs your betta fish may need more oxygen include gasping at the water surface, frequent visits to the surface, or sluggish behavior. Provide oxygen by using an air stone or adding live plants to the tank. Ensure the water surface is not covered to help with gas exchange. Keep the tank clean to prevent oxygen depletion due to waste buildup. Test the water parameters regularly to maintain optimal oxygen levels. Avoid overstocking the tank, as overcrowding can lead to oxygen deficiency. Regular water changes and filtration are essential to maintain a healthy oxygen level for your betta fish.