I don't know if 4 hr per day of sunlight is enough. Not sure. If the goldfish are trimming the roots, that could be part of the lackluster growth too.
I've wondered that too. I know full sunlight exposure would be best for plant growth but the shaded area my pond is in was kind of my only option. I've wondered about getting plants that will thrive on less sunlight like parrot's feather or something. This is my first season having a pond so the whole experience is learn as I go.
