Pond-Fish are fish, which can stay over winter in your pond
( if at least 24” deep ).
There are a couple of variations: Goldfish such as Comets, Sarasa and Shubunki, Koi and pretty new to the USA High-Fin-Sharks.
Depending on the size of your pond, there is a limit to how much fish are good.
Most pond owners tend to overcrowd their ponds which can cause algea growth and also some threatening deseases which could kill all of your fish.
The main rule here is: less is better than to much. About 1” of fish per 2’3
Always remember, your fish will grow, some up to 3’.