What would you do with a 450 gallon pond?

The pond is 6 foot by 4 foot by 3 foot high (water level) - above ground 2x4 framed and lined with a pond liner. It is run off a koi pond filter with uv. It is insulated and heated (900 watts); we are in Northern California in a valley (mild winter). It is only viewable from the top. A medium plastic plant, some cinder blocks and block pieces, some larger gravel, and pvc frame cinder block basking platform make up the current decorations and habitat upgrades. It has been running about 8 months now.

The main inhabitant is Leo a 12-inch Red Ear Slider. She is joined by about 10 swordtails, 4 platys, 6 comets, 1 green tiger barb, a couple of small cory cats, and possibly a pleco or two (all fish are small).

I have lost a few fish (3-4 swordtails, 2-3 cory cats, 1 green tiger barb, and again possibly the plecos which we put 2 in) most likely due to predation. Leo will generally only attack fish on the first night, if the make it through that, they usually last (per our experience).

This ponds main focus is Leo, who quickly outgrew all decent sized aquariums. We are relocating to the Sierra Mtns (near Truckee) and the pond will be in a heated greenhouse.

I am new to this forum and just looking for ideas, opinions, and comments. I have been keeping fish on and off for the last 16 years, but have not really done fresh since I was 18 (I am just about 30 now).

We are looking to add more fish, encourage breeding (more plants??), and algae consumption. The fish should be inexpensive, and non-aggressive, and be able to handle the lower temps 68-76.

Any decoration or habit upgrades should be inexpensive and or easy diy. The basking dock cannot go.

Thanks,
Michael

FishKeeper-16,

Thanks for your quick response. . I do appreciate your response and will look into your advice.

I would really like to keep more tropical fish though.

Since I have added my third heater, the tank has not been below 69 (last time was in early December- 67 degrees). It will be in an environment that has much better temp control next year, so 70 + will be easy.

Most info I have read on swordtails and platys are that they can handle pretty cold temps (64-82). Is this incorrect?

I do understand that the cory cats like 70+ and the pleco’s are even higher, but I was hoping they can last. I need algae control.

I know I lost at least two of my swordtails to Leo, I watched it! I also know that I have had 2 of the platys and 2 swordtails for over 4 months (the others were introduced last week).

One thing that you must remember is that this is a heated turtle pond. I do appreciate your response and will look into your advice.

Any other thoughts??