When I was young, my father really enjoyed keeping koi. We had a garden pond which was about 8 ft by 10 ft and was about 2 ft deep. This was in Malaysia where water temperatures during the day can reach between 24 and 26 degrees Celsius. Our pond was shaded by a lot of trees to avoid exposing the fish to too much sun as well as to shield the smaller fry from attack by tropical kingfishers.
We had a mix of gosanke, shusui, tancho, kinginrin and a few bekko.
When we bred our koi (usually the gosanke) we would buy large bundles of raffia strings which we would tie together to make large raffia mops. The breeding pairs (usually we would use a ratio of 2 males to one female) would be placed in a large fiberglass tank. Once the fish have spawned (quite noisily as the males chased the females, bumping against the tank and they would sometimes hit them violently to make them expel the eggs) the sticky eggs would stick to the raffia mops. We quickly remove the fish and so the eggs would be left in peace. The raffia mops mimic the function of water plants and also help to hide the eggs from the hungry parents. I'll try to find some photos of the raffia mops so I can post them later.
