Should go with native fish all the way. I got something like this in my backyard. But mine is a 55 gallon rubbermaid. Have had it up over a year and fish are even breeding. I got a Florida flagfish, bunch of pygmy sunfish, chubs, snails, clams, scuds, and a whole bunch of other organisms. I have tried different plants, water hyacinth, Iris, parrots feather, mini cattails (in a pot), duckweed, frogbit, hornwort, banana plant (lily), pondweed, anacharis etc. All worked out pretty good, right now I have mostly anacharis, sago pondweed, banana plant, hornwort, water hyacinth, and duckweed. With the growing population of fish I felt there might have not been enough natural food, so I started to seed it with daphnia and scuds, and the scuds now have a sustainable population. I have had this pond get up into the 90s and as low as the low 40s and all fish survived. However in the summer when the water got up in the 90s I added a garden umbrella and it cooled it down to lower 80s upper 70s. I have it partially buried in the ground so like the middle and bottom were cooler than the top portion. I do give the pond water changes ever so often too.