related article: Decorative Water Garden Fountain
Unless your garden pond is at least 1.50sqm and 80cm deep you should not put in any fish. If there is not more space available, better just think of a natural water garden design with different kinds of water plants. If you really want any outdoor fish pond, it's even better to start with pond depths of 1.50m or more, so water and fish in your outdoor pond will not heat up in summer time and the pond won't ice over completely in cold areas in winter time. One of the biggest mistake people do is to start to build their fish pond too small.
The bigger you plan your outdoor garden pond in size and depth, the better for the amount of fish and water plants as well as for the biological pond balance. As soon as your outdoor pond provides a healthy living space with clear water you can begin putting fish in.
Koi Fish are very common in these days, but you need to have a pool depth of at least 1m. To guarantee your Koi fish will survive an icy winter you need at least a depth under the freeze zone of 1.80m. Under proper water garden conditions Koi can grow up to 1m and it is a great pleasure watching them, especially, if they feel well in your Koi fish pond and start breeding.
Goldfish, another very common ornamented fish since all times. Goldfish-breeding was used to create numerous variations of goldfish, so today you can find different species for indoor ponds as well as for outdoor water gardens.
If you want to concentrate on domestic species for your outdoor fish pond, there are lots of local species available, like Stingray, Wolfish, or Stickleback. Be careful when you add e.g. a Red Tail Catfish, that might eat his little neighbours.
You should ask your specialized dealer, which would be proper combinations, what you should prefer and what to avoid.
With Garden Pond Streams & Water Garden Waterfalls you enrich the pool water with enough oxygen for your fish.
Consider a peaceful pond life for all your fish, which breeding features should be provided for some species and what effect the chosen species may have on the ecological balance in the fish pond as well as on the insect life on and around your garden pond. Especially, if some of your fish may prefer the "natural insect food" instead of the fish food you want them to eat.
Also Water Garden Plants & Outdoor Tropical Plants should be coordinated with each other.
If you design a water garden without fish, that doesn't mean your biotope with water plants and reed will stay without any pond life. Lots of little animals and insects will use such a water plant pond as hotbed and living space. Numerous micro organisms will develop and various water insects, like dragonflies or water beetles will appear and look for some place for their insect larva in such a water garden paradise.
As long as you don't build a backyard water garden in the center of a big city, there will come even frogs, toads and newts to your garden pond. Last not least many songbirds will use your water plant pond as watering place for a bath or some drinking water.
Building a aquatic garden without fish releases you from taking precautions against Herons at a Fishpond, one of the more unwanted experiences with a garden pond. You will make interesting observations and very soon you may realize: A natural water garden design will increase healthy growth of water pond plants and reeds and it is far from being just a silent place without any animal life.
Even your simple water garden design needs pond care and has to be checked for its water quality. Periodically water analyses will help you to stay informed about water condition and algae in your plant pond.