Dirt Less Pond Plant Suggestions

[parvenza]

Hi
I am not sure this has been addressed before and I am looking for suggestions. I have a small 40 gallon plastic pond submerged in the ground. I only have one fish left and I have had him for 4.5 years. I am struggling with a mud issue that seems to be coming from the soil around the pond between the rocks and hard to remove at this point without making the pond worse. This is a hassle because I have to keep the pond covered with a wire cage for Raccoons and now I have to cover every available opening with something so the birds don't go in and drown. Not very attractive.
Everything has to come off when I clean the pumps or take the water level way down to add clean water in.  But the pond is boring and I feel bad for the fish in it. He has a milk crate that he likes hiding in but I am looking for small plants for him that DON'T require dirt.  I know about water Hyacinth, but there isn't any this time of year. It is a dismal environment for him. I thought about giving him to someone that had a bigger pond but was told that would stress him or the fish he was being given to stressed which causes diseases.  I don't know what to do so I thought some dirtless plants (if there is anything like that) would help.
Any ideas would be appreciated.

[matherfish]

Parrot's feather can be planted in the rocks and will grow across the pond. Anacharis can be placed in the pond and weighted down to stay on the bottom, but will grow in the water under the surface. Duckweed and azolla are small floating plants but will cover the pond in a week or two.

[parvenza]

The Parrot's feather and the Anacharis sound good. I looked them up.  Had some Duckweed but I am looking for something to actually grow in the pond. The Anacharis might be good for that and the parrot's feather in the rocks. It isn't a very large pond but it needs something. These sound like they can work.  Many thanks.