A hot summer and well-fed fish can mean that the joy of the crystal-clear water of the garden pond is spoiled by excessive algae growth. In the worst case, the biotope can tip over, appear dirty green and the water surface is covered by an unsightly carpet of algae. However, there are pond inhabitants whose diet includes algae and who effectively support you in the fight against this pest.
Which algae eaters are suitable for the pond?
Effective algae eaters for the garden pond are various species of snails such as marsh snails and black mud snails, mussels and crustaceans such as European freshwater shrimp and some species of fish such as rudd. These help to reduce algae growth and maintain the biological balance in the pond.
This can:
- Snails
- Mussels and crustaceans
- or be fish.
Snails, the algae police
Unlike in the garden, where snails are more of a pest, these molluscs prove to be extremely useful in the garden pond. Not only do they use their mouthparts to graze algae from the substrate, but, like the marsh snail, they even filter floating algae out of the water. The molluscs even eat carrion and are therefore very effective in preventing the small body of water from tipping over.
If the pond is deep enough, the gill-breathing marsh snail survives the winter months without any problems in the frost-free zone at the bottom of the small body of water. She gives birth to live and is extremely fond of breeding, so there is always a baby in the cleaning crew.
The pointed mud snail, which can grow up to seven centimeters in size, is also very helpful in the fight against algae in the pond. This snail comes to the surface of the water to breathe and therefore survives even in garden ponds where the oxygen level drops sharply in the summer months due to natural warming. The beautifully colored ramshorn snail (€29.00 at Amazon) and the small mud snail are also very effective algae eaters that help maintain the biological balance.
Mussels and crabs
While snails mainly graze on algae on the bottom and on leaves, mussels and crabs specialize in floating algae. The pond mussels filter around 1,000 liters of water through their gills every day and feed on the blue and gravel algae they contain. Growing up to twenty centimeters tall, it is also visually very attractive to look at.
The juveniles of the European freshwater shrimp are also very hungry for floating algae and thus ensure clear pond water. The multiplying aquatic animals can also easily overwinter in the pond, provided it is sufficiently deep.
Are there also algae-eating fish?
Fish bring in lots of nutrients through their excretions and thereby promote algae growth. However, there are some species that also feed primarily on algae. Used in small numbers, they help to maintain the biological balance.
The rudd is well suited for smaller bodies of water, as this pretty looking fish only grows to around twenty to thirty centimeters when fully grown. The commonly recommended silver carp, on the other hand, reach a size of over one meter and are therefore only suitable for large garden ponds.
Tip
Algae in the pond are promoted by two factors: a high nutrient content and continuous sunlight, which warms the water. Therefore, provide shade at least temporarily, do not use too many animals and do not overfeed them. Strong aquatic plants in sufficient numbers remove important nutrients from the algae and ensure that the green pest does not get out of hand.