Brown Spots On Aquarium Plants: A Complete Guide To Treating Them

Aquarium plants are an irreplaceable part of any home tank. Not only do they help with oxygen regulation, but they also provide your fish with lots of hiding places. In some cases, they can act as a temporary source of food!

Thus, seeing brown spots on aquarium plants can be alarming. In today’s article, let’s break down the most common causes of this situation and see what you can do to fix them.

Brown Spots On Aquarium Plants – What Are The Causes

Aquatic plants are a little picky when it comes to their living conditions. Any undesirable changes in the environment may lead to them developing brown spots, which indicate a decline in their health.

Understanding what causes brown spots makes it easier for you to come up with the right treatment.

Brown Spots on leaves

Unsuitable water conditions

If the water’s quality has gone downhill, you are more likely to see your aquatic plants protesting by showing unhealthy physical signs. For example, some plants are only suitable for slightly acidic water, while others need a much higher pH level.

Apart from the pH level, the water’s temperature also plays a role in determining how healthy your plants are. If it is too hot or too cold for a specific species, you can expect the plants to wither.

Furthermore, the amount of metals and minerals accumulated inside your water is also worth considering. Some aquarium plants prefer living in hard water while some are more comfortable with soft water.

If you are unsure which particular facet of water conditions is causing brown spots on your aquatic plants, measure the water parameters carefully. Then, cross-check the information with the plants’ care guide. This way, you can have a better idea of how to take care of your plants.

Nutritional deficiency

Like all other living organisms, plants need nutrition to stay alive. Magnesium, potassium, nitrogen, and phosphorus are the four most vital components for plants to remain lush and healthy.

If you fail to provide your aquarium plants with these nutrients, chances are they will have brown spots appearing on the leaves.

At the same time, if the amount of nutrition is not regulated carefully, your plants can also experience similar symptoms.

For instance, having way too much phosphate prevents the plants from absorbing the nutrient. As a result, they start developing brown spots on their bodies.

It can be a bit tricky to offer the nutritional needs of different types of aquatic plants. Thus, you are recommended to go for similar plants in a home tank. This way, you will not have to struggle in meeting their needs.

Lighting problems

Light – be it natural or artificial – is an intrinsic part of photosynthesis. Without sunlight, aquatic plants cannot synthesize nutrients from water and carbon dioxide.

Therefore, having too much light or too little light can be a direct cause of plants having brown spots.

How Do I Get Rid Of Brown Spots On My Aquarium Plants?

Getting rid of brown spots on aquarium plants is much easier once you understand what causes them in the first place.

Firstly, make sure you pay attention to the tank’s water. Check all of the relevant parameters, including pH levels, hardness levels, and the number of minerals and metals inside.

Perform a regular water change to refresh the currents and eliminate the waste. Use a test kit if needed should you want to be precise about the water’s conditions.

Secondly, feed your plants with fertilizers. Be attentive regarding both quantity and quality. Some plants need more iron to grow healthily, while others prefer nitrogen.

Check and see what kind of nutritional value is needed for your plants. This way, you can ensure that aquatic plants are not underfed.

Thirdly, place your tank somewhere with a sufficient amount of light. If natural light cannot be controlled properly, consider switching to LED lights. Installing a LED light with a timer grants you the flexibility of adjusting the light exposure for your aquatic plants.

All you have to do is to pick the right colors and types of LED lights within your budget.

brown spots


1. Do brown leaves mean too much water?

Not really. Aquatic plants are designed to live underwater. Hence, exposure to too much water is not a thing. That said, exposure to low-quality water can be the cause of brown leaves.

If your water has undergone drastic changes in terms of cleanliness and parameters, expect your aquarium plants to wither and develop unusual patterns on the leaves.

2. How do you keep live aquarium plants clean?

Keeping live aquarium plants clean means you need to take care of the whole tank. This includes rubbing off debris and dirt accumulated on the walls and hidden inside tiny crevices.

You must also remove fish poop and unfinished food at the tank’s bottom since they can tamper with the water’s quality.

Another approach is to remove the algae. Algae colonies can compete with aquatic plants for food and light. Furthermore, they can bleach the plants’ original colors if left overgrown.

Using algae eaters or simply removing them by hand are recommended.

3. Do live plants make aquariums dirty?

Live aquatic plants only make your home tanks dirty when they decay. If the plants die and are left to rot inside the tank, they surely will dissolve themselves into foul-smelling matters.

Eventually, they will affect not only the aesthetic aspect but also the general well-being of your aquariums.


Brown spots on aquarium plants are simply a way for plants to signal problems. If you detect these issues early on, make sure to treat them right away.

Timely intervention minimizes the chances of your plants dying and thus, ensures the quality of your home tank