Do dead betta fish disintegrate if left in water?

Yes, dead betta fish can disintegrate if left in water, although the process can take some time. Bacteria and other microorganisms in the water will begin to break down the fish's body, leading to decomposition. Factors such as water temperature and the presence of other organisms can influence the rate of disintegration. However, it's generally advisable to remove dead fish from the aquarium promptly to maintain water quality and prevent harm to other aquatic life.