Aquaculture
Aquaculture is farming on water. Many of the same principles as farming on land apply, and there can also be synergy between land-based and water-based farming - for example, the tadpoles that will occur endemically in ponds in most climates are an excellent food source for chickens.
Because fish are cold-blooded, and because water provides buoyancy so they do not have to expend energy to hold themselves up all the time, they are much more energy-efficient organisms than land based animals.
Large stones placed in a pond will serve as a heat sink, making the water cooler in hot weather and warmer in cool weather.
Growing reeds helps to oxygenate the water. Freshwater reeds grow much faster than any land-based plants can, so make a good source of feed for herbivorous animals

See also aquaponics, a more controlled method of growing fish.