I like the look of your pond
. I have a net over my pond which is attached by hooks all around the edges, i just unhook the net when i intend spending a day in the garden. Its harder with your pond kaz because of the plants. Have you had any dragonflies , damselflies frogs or newts kaz ?. The reason your fish have survived is probably due to that all you plants provide cover for the young ones to hide in , so keep things as you are kaz, just do a tidy up as you have and you could use a small net to scoop the bottom bit by bit to remove debris like has been mentioned
. love the iris's.