Koi, goldfish, grass carp: fish for the garden pond

A garden pond with fish can become a very special place in the garden. Whether small goldfish or rather popular koi carp - there are plenty of fish. But not every garden pond is suitable for every species. We will explain what you have to look out for here.

Your garden pond is finished after a long work. But the most important thing is still missing to make it a real eye-catcher in the garden: the fish. Goldfish, koi, grass carp and wall lizards are not only beautiful to look at, they also serve an important purpose. For example, they eat mosquito larvae and thus often prevent a nuisance. In addition, the use of a pump and filter can be dispensed with.

But not every type of fish is suitable for every garden pond. It is therefore important to inform yourself well beforehand.

How many fish can live in your pond depends on its size. Avoid keeping them alone in any case, because fish also feel more comfortable in company. If you have decided on a fish species, you still have to bear in mind that the animals should only be used when sufficient "food" has accumulated in the pond. In some cases, this can take up to a year.

In the following we introduce you to "ideal" pond fish and problematic species that you should rather avoid.

Fish species for small to medium-sized garden ponds

Densely planted retreats for the fish and a water depth of at least one meter are essential.

a) Moderlieschen (Leucaspidus delineatus)

Moderlieschen are local schooling fish that grow to be between eight and ten centimeters in size and have a slim body with shiny silver scales and a bluish sheen. They are very swim-loving fish that mostly stay close to the surface of the water and spawn in April or May.

Moderlieschen mainly feed on small creatures such as crabs, insects and insect larvae. They also get along well in winter. Since individual fish appear rather inconspicuous, at least seven to twelve fish should be used. Good to know: Moderlieschen breed care. The female places spawning cords on the stems of aquatic plants, the male guards the spawn and fans it with oxygen-rich water.

Moderlieschen are shoaling fish that are between eight and ten centimeters in size.

b) Bitterling (Rhodeus amarus)

Bitterlings have a length of about seven centimeters and, unlike moderlies, live more at the bottom of the pond. Here, too, at least five fish should be bought. They are peaceful animals that feed on water fleas, plant foods and flake food, for example. If you want the bitterlings to reproduce, you can help with a pond shell that they place in the pond. The eggs are then placed in the interior of the living shell and fertilized there, the larvae hatch after a few days.

Bitterlings are about seven centimeters long and live more and more on the bottom of the pond.

c) Minnow (Phoxinus phoxinus)

The minnow is about ten centimeters tall and requires clean, oxygen-rich water. Therefore, ventilation can make sense. Minnows are also schooling fish and should live about ten in the pond. They also prefer cooler water temperatures. The food consists mostly of plant food, but they also eat smaller aquatic animals and dry food.

Just like moderlies, they usually stay on the water surface and learn very quickly where to find food. But be careful: If the oxygen content drops in winter due to the formation of ice, the few minnows survive.

Minnows are about ten centimeters tall and need clean and oxygen-rich water.

Photo: iStock / y-studio

d) goldfish

As popular as goldfish are, they are only conditionally suitable for a small pond. They grow up to 30 centimeters tall and like to gobble, so that the water is often cloudy and a filter is useful. The spawning season is from March to May. Do not be surprised at the gray-black color of the juvenile fish, because from the second year onwards, depending on the breeding form, they will be speckled in satin red or red and white.

Goldfish are omnivores and very insensitive to lack of oxygen, heat and diseases. Furthermore, they are particularly sun-loving and reproductive. The females lay up to 4, 000 eggs in the water, which are only then fertilized. Another big advantage of goldfish is that they get along well with other fish.

Goldfish grow up to 30 centimeters in size and like to gobble. This often makes the water cloudy.

Photo: Fotolia / selezenj

e) Golden orfe (Leuciscus idus)

The gold orfe is a breeding form of the Alands (a carp fish) that does not occur in the wild in this way. The fish grow up to 45 centimeters in size and prefer to be in the shoal, so there should be at least six fish in the pond. They are very active and swim a lot, so make sure you have enough space. They prefer to feed on small aquatic animals, flake food and food sticks.

Orfen is available in three colors: gold, silver and blue. If you keep all three variants in your pond, you have to expect that the offspring will have mixed colors. Good to know: Goldwerfen like to jump. Therefore, make sure that the animals cannot jump out of the pond.

Goldwerfen are a breeding form that do not occur in the field. They grow up to 45 centimeters.

Fish species for large ponds

a) Koi carp (Cyprinus carpio)

Koi carp are available in very different optical variants, because they are bred in many color games. Their origin is in Japan, where nobles held them as status symbols in the 19th century. They can grow up to one meter long and have a very slim body. They also feel most comfortable in warm water at around 24 degrees. Their spawning season is from May to July.

Basically, koi feed on almost everything: plants, worms, snails, fish fry - but also the regular addition of feed mixtures is always welcome. Koi carp must always be cared for in a group because they are very social. Make sure that your pond has a volume of at least 20, 000 liters and a depth of at least 1.5 meters to ensure that it is kept appropriately.

Since carp are intensively burrowing pond fish, a filter system is essential. The trustworthiness of the koi carp is special, so they even eat out of your hand when the occasion arises. Even today, koi carp are still a popular fish for fish lovers, who spend large sums of money on special specimens. Fortunately, carp have a long life expectancy of around 70 years, so that as an owner you have something of the animals for a very long time.

Koi carp are bred in different colors and can grow up to one meter long.

Photo: Alamy Stock Photo / KHALED KASSEM

b) Sterlet (Acipenser ruthenus)

The sterlet belongs to the sturgeon family and grows up to 80 centimeters. They are very keen to move and require a water depth of at least 1.5 meters. A filter system is also important for this type of fish, because the animals need oxygen-rich, cool and clean water to survive. Sterlets mainly eat small animals at the bottom of the pond. In garden ponds, you should definitely feed them with stuffing.

Make sure that no thread algae grow in the pond, because the sterlets get caught quickly in it. In addition, sterlets live up to 20 years = " and can become tame over time.

The sterlet is up to 80 centimeters tall and requires a water depth of at least 1.5 meters.

Photo: Fotolia / Vladimir Wrangel

Problematic fish species for the pond

a) grass carp (Ctenopharyngodon idelle)

Grass carp are up to 60 centimeters tall and are often referred to as algae eaters. But they usually only eat thread algae when nothing else is available. So first all other pond plants such as water lilies will fall victim to the grass carp. Grass carp are best suited for very large ponds where cloudy water does not bother anyone. Their spawning season is in high summer because they need a very warm water temperature of around 26 degrees Celsius to reproduce.

Grass carp grow up to 60 centimeters long. They are often referred to as algae eaters.

b) Three-spined stickleback (Gasterosteus aculeatus)

The three-spined stickleback is a small, local fish, which is not a problem in small numbers in the garden pond. But sticklebacks multiply en masse and extremely quickly. Sticklebacks also eat tadpoles, fresh brood, insect larvae, water fleas and other small animals and are not ideal pond fish due to their aggressiveness.

The three-spined stickleback is a small fish that reproduces in abundance and extremely quickly.

Photo: iStock / Africanway