Betta fish are capable of eating aquatic plants, but they typically don't use them as their main source of nourishment. Betta fish are omnivorous, mainly feasting on small aquatic insects, plankton, and benthic organisms. When food is scarce, betta fish will turn to aquatic plants as a supplementary food. This is because aquatic plants are packed with nutrients such as protein, carbohydrates, and cellulose, which are beneficial to the growth and health of betta fish to some extent.
Moreover, it's beneficial to include aquatic plants when raising betta fish. Aquatic plants can purify the water quality and replicate the natural ecological environment, which is good for the well-being of betta fish. Recommended aquatic plants are Egeria densa and Nymphoides indica. These aquatic plants have a high survival rate, reproduce quickly, and are easy to look after.