Fishponds are usually artificial ponds for fish cultivation. Of course one can also call his garden pond or koi pond a fish pond, but in common usage breeding ponds in the fishing industry are meant.
Construction of a fish pond
In contrast to garden ponds, which are provided with pond foil or other seals, a fish pond usually has no artificial barrier layer to hold the water.
A fishpond is usually built in areas where the groundwater is high enough to fill the pond. Fishponds often have an inlet and outlet via a stream or spring. If the inflow is via a stream, the inflow of the fish pond should be separated from the breeding pond with a fine-meshed grid, in order to prevent predatory fish from entering its breeding program.
You should also check your fish stock regularly. A fish pond with a direct inflow from a spring will usually only be suitable for breeding cold water fish, depending on the attainable water temperature. Since spring water is usually low in oxygen, it must be enriched with oxygen for fish farming. Most coldwater fish require oxygen-rich water. Spring water in most areas of the USA has a temperature around 45 to 50 F.
In standing and thus warmer fishpond mainly carp but also zander and pike are kept. Rainbow trout, brown trout and char are cultivated in the oxygen-rich water in colder and flowing fish ponds.
Ideally, the inlet of a fish pond can be shut off or diverted to drain the water. This makes fishing easier and when the pond is dry for a period of time, fish parasites and diseases are also contained. If the water cannot be drained, the fish are caught with a trawl net. Fish are usually not bred in a fish pond. Normally, young fish that have grown up in rearing tanks are used and raised. It, therefore, corresponds more to fattening than breeding.