A sight that most aquarium owners are familiar with – and many even fear: the aquarium plants are turning brown. There can be many reasons why plants in the aquarium turn brown. Some of these are completely harmless, others can be an indication of a care or transport error. If you want to know the reasons why aquatic plants turn brown, you should read here. We give you a brief overview of the most important reasons why the plants in the aquarium turn brown.
Aquarium plants are turning brown – cause #1
Air leaves are dropped
Most of the plants that we keep in our aquariums are not “real” underwater plants but grow emersed in nature – i.e. above water – for example in swamps or wet areas. If there is heavy rainfall, such as in the tropics during the rainy season, the regions where the plants grow are flooded. The marsh plants are now in the water and immediately adapt to the new conditions:
- The plant forms new, physiologically differently built underwater leaves.
- The old air leaves turn brown over time and are shed by the aquatic plant.
This is why new aquarium plants often turn brown after being planted. The nurseries produce the aquarium plants in greenhouses. If they are used in the aquarium, the same process takes place in nature. Many aquarium owners do not know that most of the plants that are grown for the aquarium grow emersed. You think the aquarium plants are turning brown because they are sick, but there is no need to worry.
Aquarium plants are turning brown – cause #2
Mechanical damage caused by aquarium inhabitants
If you notice that the aquarium plants are turning brown, you should take a closer look at the leaves of the affected plants: Mechanical damage can be a cause of the aquarium plants turning brown. Above all, the aquarium inhabitants are responsible for:
Snails tirelessly scrape the surfaces in the aquarium with their eating tools. The upper skin of the leaf, the epidermis, can be scraped off.
Suction catfish, which are very popular algae eaters in the aquarium, can also damage the epidermis of the leaves.
Due to the damage, an affected leaf initially turns brown and can then die off. When setting up an aquarium, you should therefore always adapt the aquarium plants to the existing stock. The plants for perch aquariums, for example, differ greatly from the plants for a discus aquarium or the varieties that are chosen if you want to set up a shrimp aquarium.
Aquarium plants are turning brown – cause #3
Iron deficiency leads to discoloration of the aquarium plants
When was the last time you determined the iron level in your aquarium? If you notice that the leaves of the aquarium plants are changing color, you should do it. With an iron deficiency, the leaves of the aquarium plants do not turn brown, but they do turn yellowish, look unhealthy, and are hardly green anymore. Due to acute iron deficiency, the aquatic plant is not able to form chlorophyll.
Aquarium plants are turning brown – cause #4
Diatoms or brown algae are in the aquarium
Have you ever looked closely when you noticed that your aquarium plants are turning brown: is it really the leaves themselves that are turning color? If there is a brown layer that can be easily wiped off with a finger, the aquarium has diatoms. They are also called brown algae because of their brown color. They like to appear after a new setup of the aquarium or after large water changes. However, not only do the leaves of the plants in the aquarium turn brown, but also surfaces such as windows or hardscapes. Brown algae is not a problematic type of algae in the aquarium. They usually go away on their own. Incidentally, the leaf of an Echinodore with brown algae infestation can be seen on the title page.
Aquarium plants are turning brown – cause #5
Cryptocoryne blight affects water chalice stock
If only the cryptochromes in the aquarium, but not the other plants, turn brown, it may be cryptocoryne rot, also known as water cup rot.
It partly ensures that entire stocks are destroyed in a short time. The leaves of the aquarium plants turn brown, literally fall apart and dissolve. The causes of cryptocoryne rot are controversial and there are various explanations as to how this phenomenon can occur. If one used to assume an illness, today external factors such as physiological disorders are usually cited as the cause. While some aquarists have no problem with this phenomenon, others report regular flare-ups every few years as the cryptocoryne turns brown and decays.
Aquarium plants are turning brown – cause #6
Vallisneria after insertion or transport
If a look into the aquarium shows that the Vallisneria are turning brown, while the other aquarium plants are thriving, then the Vallisneria was probably replanted not too long ago. These aquarium plants are very sensitive to transport. The outer leaves of representatives of this genus often die off after planting because the plant still has too few new roots to feed the entire leaf mass. Once the roots have formed in sufficient number and size, new, strong, green leaves will emerge. If Vallisneria turns brown, this can also be due to transport damage caused by heat or cold. But that’s easy to avoid. You can read tips on how to ship aquarium plants correctly in our little guide.
Aquarium plants are turning brown – cause #7
Light makes the leaves darken
Many plants form red-brown leaves close to the surface. If the aquarium plants turn brown at the tips of their shoots, this does not mean that they are dying – even if it often looks that way too inexperienced aquarists. The reason why the leaves of aquarium plants turn brown is the bright light on the surface. By storing brown pigments, the aquatic plant tries to protect itself against this. The process is similar to human skin, which also turns “brown” with increased exposure to the sun. The phenomenon is also easy to observe on leaves that stick out of the water, where the light hits them unhindered.
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