Ok I need tons of help. First, I want to know how many fish I can have. I started off with 15, 4-inchers (a combo of comets and koi) but 8 of them died and I'm heartbroken. I think it was because of bad water quality, but it's 6 comets and 1 koi now. My pond is divided up into 3 sections. I'll attach a picture. There is a giant filter attached to the fountain that I have just installed. The water circulates through the three ponds and back into the filter and through again. In the other pond, you can see the tiny fountain, which is also being pushed through a filter. In addition, I have two water lily pad plants, which you can't see because they're still underwater. The measurements of each pond are approximately (77x63x23), (28x32x17), and (94x77x19). I don't know how many gallons that is, but how many koi fish could it hold and how should I divy them up?
Secondly, is there enough oxygen and circulation?
Third, all I add is barley and pond prime. I'll start up food when it's consistently in the 50s (still cold here) in addition to adding surface plants. I just took out the winter heater. Does that sound good or am I missing stuff?
If I wanted to breed, do I have the space, and how would I go about that?
Anything else, you notice me doing wrong, please cue me in! Thanks in advance for the help.