Most do not like more than a couple of inches of water over them and their foliage will grow out of the water. Examples include the Marsh Marigold, Bog Arum, Water Iris, and Bull Rush. Finally there are bog plants. They like to have their feet damp constantly but never water-logged. We don't fertilize our water garden plants more than once or twice a season as the solute created only exacerbates algae problems.
Fish add a different kind of life to ponds.
Goldfish are ideal for the beginner gardener as they forgive mistakes readily and do not require a filter. Fish also eat larval mosquito and algae. Koi, it is said, can be taught to eat out of their owners hands. They are more expensive then goldfish, they like to eat the roots of plants, and they disturb bottom matter interfering with clarity. Marginal plants should be cut down so that only a few inches remain above the surface.