Excessive algae growth in the pond is not just a visual problem, it can also cause considerable problems within the mini-ecosystem. In addition, the green plague is difficult to remove, which is why many pond owners are only too happy to rely on the support of algae-eating fish. You can read in our article which species that are often offered actually eat algae and which do not meet this expectation.
Pond fish as algae eaters
Sometimes, however, all the precautionary measures and the most beautiful planting do not help. In this case, the five fish species listed here do well both as algae killers and as ornamental fish in the garden pond. However, you must not expect these species to completely grow algae remove and the water becomes clear again by itself: That can also be done Algae destroyer fish do not. Here, too, only a combination of eliminating the cause, suitable pond planting and well-considered fish stocking will help.
Grass carp (Ctenopharyngodon idella)
The large and heavy grass carp are very suitable for combating algae, because they only feed on algae and other underwater plants. But be careful: Due to their size, they are only suitable for really large garden ponds. Also make sure that there are very lush vegetation, as these fish are insatiable and, if there is a lack of food, also like to eat ornamental plants or the bank vegetation. If necessary, feed with freshly mown grass.
- Size / length: up to 120 centimeters, up to 40 kilograms in weight
- Lining: Aquatic plants, algae
- Propagation: from temperatures of 20 ° C, multiply very quickly
- Pond size: at least 20 square meters per fish
- Water quality: high oxygen content, waterfalls, fountains and / or streams are good for this
Moderlieschen (Leucaspius delineatus)
The local Moderlieschen is also an algae-eating fish species with an almost gigantic appetite. The small, silvery fish are also easy to observe, as they usually swim close to the surface, themselves like to hide between the aquatic plants and occasionally also mosquitoes whirring close to the surface of the water to hunt.
- Size / length: up to about 10 centimeters
- Lining: Phyto- and zooplankton, algae, mosquitoes
- Propagation: Water temperatures over 18 ° C, oviposition on aquatic plants
- Group size: Schooling fish, at least 10 to 12 fish
- Pond size: at least 2000 liters
- Pond depth: at least 80 centimeters (for wintering! Pond must not freeze through)
- Water quality: high oxygen content, low nitrate content
Rudd (Scardinius erythrophthalmus)
Ruddy feathers are also busy eaters of algae and are therefore well suited for destroying algae growth. However, these pretty fish also like to eat other aquatic plants, which is why such a population is quickly decimated and with a little bad luck you will no longer have any plants in the pond. It is best to bow with regular feeding and the preferred planting of aquatic and bank plants with leathery,
- Size / length: 20 to 35 centimeters
- Appearance: red back, red fins
- Lining: Insects, zooplankton, small invertebrates, aquatic plants, algae
- Propagation: in shallow water (approx. 20 centimeters depth)
- Pond depth: at least 70 centimeters
- Group size: at least 5 pieces, at best 10 to 15 pieces
- Water quality: Oxygen-rich, light flow, filter and pump necessary
Tip: You can estimate the water quality based on the back and fin color of the rudd: If this is good and the water is rich in oxygen, the typical red color is particularly strong. However, it fades if the quality of the water is poor, which you should take as an alarm signal - the sensitive fish then die quickly, and algae growth is also promoted.
Silver carp (Hypophthalmichthys molitrix)
The silver carp, which can grow up to a meter long in the wild, has become a problem in some waters due to its voracity. Once exposed to combat algae, it also eats other aquatic plants when there is a lack of food - which results in bare lakes and ponds and the resulting lack of oxygen. So always make sure that the rustic fish always have enough to eat and feed them if necessary.
- Size / length: up to 60 centimeters
- Lining: Phytoplankton, good algae eater
- Group size: at least four animals
- Pond size: at least 20,000 liters
- Pond depth: at least 80 centimeters, better more
- Water quality: high oxygen content, stagnant to easily flowing water
Pennant carp (Myxocyprinus asiaticus)
The pennant carp native to China - sometimes called the batfish due to its characteristic appearance - is a very good algae eater. However, like all carp, it is only suitable for large garden ponds and also has very special requirements for the water quality. In contrast to many other pond fish, this species needs the cleanest possible, low-nitrate water and a slightly acidic pH value. If you want to keep pennant carp, you should make sure that these requirements are met, otherwise the animals will quickly get sick and die.
- Size / length: usually 40 to 60 centimeters, in exceptional cases more
- Lining: Phytoplankton, good algae eater
- Group size: at least five animals, easy to socialize with Koi
- Pond size: at least 20,000 liters
- Pond depth: at least 80 centimeters, better more
- Water quality: high oxygen content, low-nitrate water, pH value slightly acidic to neutral
Alleged algae eaters in the garden pond
Various types of fish are considered ideal "algae eaters" on the Internet and in stationary specialist shops. touted, which keep the garden pond free of annoying algae and thus the water clear and clean would. Unfortunately, this is a wonderful dream, but it doesn't work in practice. Some of the "water-cleaning" fish hardly eat algae or are not at all suitable for the garden pond because they need completely different living conditions.
These fish species are considered to be algae-eating, but for various reasons they are not:
- nose(Chondrostoma nasus): is at home in (strongly) flowing waters
- Gold minnow(Pimephales promelas): mainly eats insects, water fleas, small crabs
- Gudgeon(Gobio gobio): eats crabs, worms and other small animals from the pond floor
Tip: The best way to keep your garden pond free of algae is to combat the causes of algae growth. Above all, this includes a high nutrient content in the water (e.g. B. fertilizers washed away from the neighboring lawn by seepage water) and a high water temperature. The latter can be avoided, for example, by shading the water surface, for example with the help of taller aquatic and bank plants.
What else helps: molluscs and crustaceans
In addition to fish, water snails, pond clams and native crustaceans also like to eat algae. These species in particular are often kept in the garden pond for the said purpose:
- European freshwater shrimp (Atyaephyra desmaresti)
- Small pond snail (Galba truncatula)
- Ramshorn snail (Planorbarius corneus)
- Mud snail (Lymnaea stagnalis)
- Pond snail (Viviparidae)
- Pond clam (Anodonta cygnea)
But be careful: The animals multiply very quickly in good conditions, which can quickly lead to a lack of food. As a result, they not only eat the unwanted algae, but also other, desirable aquatic plants. Therefore, you should not let the stock get too large and fish out excess snails if necessary.