I maintain a bog pond that is a 160 gallon pre-formed plastic pond about 3 X 4 ft. with a shallow 12-18 inch bay area at each of the four corners. The water in the bays is about 2-3 inches deep. The pond is 18 inches deep at its deepest with the deep part in the ground. The bays sit on top of the ground. I have 30 inch high fencing on the west and south sides covered with autumn clematis to keep the pond from getting too hot from afternoon sun.
The pond is filled year-round with rainwater that I collect from my house roof. My rainwater has a pH of 5 to 5.5, and the water in the bog typically has a pH of 5.5 to 6.0 measured with pH paper strips. Outside of three or four pitcher plants in foam floating planters, I add several water hyacinths which reproduce well in that shallow of a water body. Most of the water surface is covered with duckweed, which I remove some of every few weeks to provide open water to feed the fish. There is no filtration or aeration.
The fish are fed daily with TetraMin flakes ground fine between the fingers. I add a dozen or so pygmy sunfish in the spring and harvest 50-60 in the fall.
During the winter, the fish are kept in unheated 15 and 20 gallon tanks in my basement. Each tank has a sponge filter and contains aquarium strain Najas. There are overhead aquarium lights on a 12 light - 12 dark hour timer. The water is the same rainwater I collect off of my roof. Temperature typically ranges from 76 degrees F in the fall to a mid-winter low of 54 degrees F. The fish are fed daily on finely ground TetraMin flakes and are fed newly-hatched brine shrimp every other day. I find that feeding brine shrimp only every other day keeps me from having a hydra problem. I think that the pygmy killies reproduce in the aquaria as well. I don't notice baby fish, but I seem to end up with more fish that I start with. Each tank typically starts out with 15-20 fish, but ends up with 40-50 after a few months. The Najas gets pretty thick in areas that could easily hide the babies.
Hope this helps, Phil Nixon.