Yes, Corydoras do eat plants in their natural environment. They are omnivorous scavengers that feed on a variety of items such as organics matter, small invertebrates and even algae. Plants can provide an important source of nutrition for these bottom-dwellers, helping them to maintain healthy growth rates. It is best to not keep them with any delicate or slow-growing species though, as they could quickly consume all available food sources before the slower growing plants have had time to recover.