Where are you located?

In zone 10 you should have a fair selection of plants to chose from. There are likely plants growing wild around you that would do well depending on how much rain you get. There is a big difference in that throughout zone 10. Elephant ear would be a good choice so long as it is in a pot sitting in the water or planted in moist ground. The water may be too shallow for waterlilies. The local Cooperative Extension Service will possibly have a list of suitable plants.

If the rock face and the pockets are consistently wet, there are a lot of things you can use. Any small aquatic would work well (provided the roots stay wet). Star grass comes to mind as a possibility. Small clumps of aquatic bacopa would also work. You might even be able to grow water lettuce or water hyacinth there.

There are a few terrestrial plants that might be successfully grown there. Impatiens do well in a constantly wet environment, but only if the soil is carefully washed from the roots prior to tucking them into their nitch. They don't like constantly wet soil, but will do great bare-rooted.

I'm sorry but with water that shallow the chances of fish living through summer heat are slim....

Agreed. This is not a pond, it's a fountain.

I'd definitely be more concerned about the fish at this juncture than what plants will grow there. The first thing is to provide them some shade/cover & give them some relief, even if it's a temporary one while you make other arrangements. I'd move them to a holding tank at the very least. How many do you have? And what type of filter do you have?

Is there ample space to add a deeper extension so the fish could surive/thrive? Pics of your entire fountain adjacent area would be halpful here.

Thanks to everyone who answered my questions about the plants.

In regards to the fish;
- it is difficult to see in these photos but the fish can easily get to the backside of the rock. About 60% of the volume of the water is exposed, about 40% is behind the rock and completely shaded. So, the fish can go under the overhang or the plants on the front side of the rock (which is where they tend to be found), or completely behind the rock for full shade and presumably cooler temps.
- there are about 10 small goldfish and the 1 pleco at this point. I don't really plan on getting too many more than that, assuming we keep this group going. And I realize that this is less than an ideal situation for fish, so I'll be happy if we can keep some gf kicking around in there and leave it at that.
- we live less than a mile from the ocean. Our temps might get to 90 degrees >10x a year. Honestly while I understand that the water temp matters, I am not worried about anyone getting cooked.
- I made a filter out of an upside down planter box, some air filter mesh and our pump. I could add bio balls if it will make a difference.
- This house is a rental so I am not going to kill myself over making a perfect environment for goldfish. I would love for them to thrive, but if they don't I can have a nice fountain with plants that makes the hummingbirds happy. They already are thrilled with the set up.

Thanks again for the help.

Hello tundrah.

I understand the fact that your home is a rental and you desire to keep any investments at a minimum. That acknowledged, and after reading your comments several times, the best I can offer is to suggest you give your fish away to good homes & enjoy your happy hummingbirds.

blessings,
~digger