Why Is My Pleco Turning White? [6 Possible Reasons]

If your pleco is turning white, it means that it could be dying and needs your immediate attention. The most common reasons a pleco will turn white are poor nutrition, stress, disease, or inadequate tank conditions.

We will discuss why your pleco is turning white and things you can do to prevent it from dying. 

1. Poor Nutrition

Plecos are popular for freshwater tanks because they are algae eaters. Fish enthusiasts often mistake their algae-eating preference to mean that pleco’s do not require any other food. Unfortunately, this misconception can lead to your pleco slowly starving to death.

Plecos are actually omnivores. Meaning they require a more well-rounded diet that includes protein and vegetables. 

Plecos are also nocturnal. Fish hobbyists like to feed their plecos disc or tablet foods as well as zucchini, shelled peas, cabbage, kale, and other vegetables two times a week at night. 

Because there are almost five hundred different species of Plecostomus (pleco), it’s a good idea to look up your exact type of pleco to learn what foods are recommended for it.

2. Your Pleco Is Experiencing Stress

Plecos are sensitive to stress. Symptoms of stress in fish include color fading, weight loss, hiding, and glass surfing. 

Stress can come from various sources, including aggressive tank mates, temperature fluctuations, wrong pH, underfeeding, disease, or a sudden event like being dropped. If you think your pleco is stressed out, try to identify the source and correct the problem.

If you believe the source of the stress is coming from one of your pleco’s tank mates, you should remove the pleco from the tank until you can figure out how to resolve the problem. Sometimes, you may be able to minimize fish aggression by better redesigning the ‘aquascape’ of your tank. 

Plecos love hiding in dark places, for example. So you may want to consider if your tank gives them enough hiding places. If you cannot get your fish to stop being aggressive towards each other, you may have to consider permanent, separate tanks.

3. Your Pleco May Be Sick

Fish can get sick and die just like people. A few common diseases that pleco are prone to get are:


Dropsy is a build-up of fluid inside the body or tissues. Dropsy is actually a symptom of some other underlying disease, such as bacterial or parasitic infections.

Whatever the cause of the disease, whether contagious or not, if you believe that your pleco is sick, you should quarantine it to protect the other inhabitants of the tank. 


Also known as the ‘white spot disease’ or ick. Ich is a parasite that attaches itself to your fish’s gills, fins, or body. It feeds off of your pleco until it reaches maturity, then drops off and replicates itself. 

A pleco with Ich may look like it has tiny, white crystals all over its body. 

Introducing new fish to your tank without quarantining, a poorly maintained tank, rapid changes in temperature or pH levels are just a few of the things that might cause an Ich outbreak.

Fin Rot

Fin Rot, like Dropsy, is another symptom of an underlying problem. Fin Rot will be first noticed at the edges of the fins, destroying the tissue until it reaches the base of the fin. 

Once it reaches the body, it continues to eat away at the body, called ‘body rot.’ If Fin Rot reaches the body, it is usually fatal as the pleco will not be able to regenerate the lost tissue.

Fin Rot is caused by bacterial or fungal infections usually brought on by poor water conditions, injury, stress, or poor diet.

Hole in the Head

Hole in the Head (HITH) or Head and Lateral Line Erosion (HLLE) are essentially the same things. This disease makes it appears as if your pleco have little pits or holes developing on their heads. Some have likened it to their fish appearing to be eaten alive.

Unfortunately, there doesn’t seem to be a lot of understanding as to what causes the disease. This can make treatment difficult. The common culprits are stress, water issues, or nutritional deficiencies.

4: Alkalinity, Temperature, and pH Problems

A freshwater fish from South America, plecos have specific tank environment needs; a pH of 7.0 to 8.0, alkalinity of 3 to 10 dKH, and a temperature range minimum of 74 degrees Fahrenheit and a maximum of 80 degrees.

To maintain this very specific environment, you should test your tank water regularly with an aquarium test kit. Generally, once a week is considered adequate. However, if your fish are sick or seem to be under stress, it is advisable to test every two to three days until the problem is resolved.

5: Acclimitazing Your Pleco To It’s New Home

Sudden changes in the environment are quite stressful for your pleco. Be sure to gradually introduce your pleco to its new tank. 

When you buy your pleco, make sure to find out the temperature, pH, and alkalinity that the fish store is keeping their plecos in. When you get your pleco home, set the bag in your tank, and slowly add in small amounts of your tank water into your new pleco’s water to help it adjust.

6: Your Tank Is Too Small

Plecos can get quite large. They have an average size of 24 inches! When you purchase your pleco, you should be sure to know how large your pleco will get when it is mature. 

It is recommended that plecos be placed in tanks that are from 50 to 100 gallons.


Plecos can be a wonderful addition to any fish tank. Their beautiful colors, larger sizes, and algae-eating habits make them both fun and useful addition. 

But if you are asking yourself, ‘why is my pleco turning white?’, it could be a sign that something is wrong, and you should take immediate action. Whether the problem is nutrition, stress, tank conditions, or something else, if you diagnose the problem, you may be able to help your pleco before it gets too serious. Your pleco will thank you for it!

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