This leads to major water activity, something that plants and fish find it difficult to tolerate. Ponds of this type are generally not planted.
2.2: There are ponds intended for keeping fish.
For example, koi carp. Fishponds generally contain no or only very few plants. Fishponds are not kept clean through the biological action of plants but by the use of filters, which take over this task.
The effects are normally excellent.