Why Do Plecostomus Change Color? {The Top 5 Reasons Why This Happens}

Are you seeing your Plecostomus changing color? Is it stress or illness related? This article is meant to assist anyone who is wondering why their Plecostomus is changing color.

Why Do Plecostomus Change Color? The Plecostomus may try to camouflage itself to blend in with the substrate or surroundings in the tank. Mood changes, stress or fear could also cause the vibrancy of your Plecostomus to be affected. 

What Are The Reasons Why Plecos Change Color?

There are a number of explanations to color changes that depend on the timing or situation your plecostomus is in. Here are our top 5 reasons why your plecostomus changes color:

  1. Water Changes
  2. Lighting
  3. Substrate
  4. Mood 
  5. Stress

1. Water Changes

A water change for example, can cause fear or a general disliking to make your plecostomus lose color, become dull or pale and possibly stressed to the point of weakening their immune system.

Try to perform smaller water changes more frequently instead of a larger one all at once. The sudden change could cause your plecostomus to turn whiter.

2. Lighting

Your plecostomus would appreciate dark or dim areas, shaded spots and plenty of darkness through the night. If the aquarium lights are too bright or there’s isn’t enough space to get away from bright areas, then your plecostomus might change or lose color.

Plecos enjoy being more active at night. During the day, try to add more hiding spaces for them to rest.

3. Substrate

If you have a white substrate, you can expect your plecostomus’ color to not be as vibrant. The desire to camouflage with the spaces where they mostly reside or scavenge is a likely indicator of color changes. A dark gravel compared to light gravel can alter the color of your plecostomus.

4. Mood

Your plecostomus might be trying to tell you something. It might not be stress related. If you notice the color of your plecostomus is eye popping and beautiful, then all is well with feedings, relaxing spaces and water quality.

A pleco in a good mood has plenty to eat. A mix of veggies during the week along with pleco specific pellets and sinking flakes will bring out the best in aquarium plecos.

5. Stress

Stress will definitely affect the color of your plecostomus. Pale discoloration is one thing, but patches, fungus, rotting or white spots indicate that stress has allowed for illness to take over.

A weakening of the immune system coupled with stress allows parasites or bacterial infections to alter the appearance and overall wellness of your plecostomus. A larger sized tank will help reduce stress levels from excess waste and overcrowding.

Is My Plecostomus Using Camouflage?

If your plecostomus is not sick, then the color change you see is on purpose. This is a form of camouflage present in most plecos. Blending into the surroundings is a sign of comfort, safety or fear. In all cases, it’s a response to hide or become a part of the background.

If you notice your plecostomus acting the same as usual, there is no concern. Your plecostomus may lie motionless for hours in the same spot and in subtle changes, take on some color resemblance of the space.

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How Do I Know If My Pleco Is Stressed?

Our best skill is our power to observe for anything that seems off in our tank. We react accordingly or enjoy the effortless moments when we’ve done well and our ecosystem is thriving.

Then comes a stressed plecostomus all of a sudden. Look for these signs:

  • reduced activity
  • lack of appetite
  • excessive hiding
  • breathing heavy
  • gasping for air
  • erratic swimming 
  • injuries or abrasions
  • spots
  • color change to a darker shade
  • color change to a lighter shade

Color changes indicate stress as well. Check your water parameters to make sure if spikes in ammonia or nitrites may be causing it. If there is only one of the symptoms present, continue to observe for more. Once you see more, it’s time to react with:

  • a quarantine tank
  • enriched nutrient sources of pleco food
  • gradual water changes
  • medication

What Color Should Plecos be?

Plecos come in a variety of shades and spots. Black, brown or gray bodies usually contain a pattern of spots that are light in color. The bottom of a pleco is also lighter than the overall look and shade everywhere else.

People who use white sand may see a brighter or whiter colored pleco. Someone using a dark gravel substrate may expose more black, brown or gray colors. Heavily planted tanks could promote darker or brighter olive colors.

Why Is My Pleco Getting Lighter In Color?

Your pleco could be turning brighter, duller, paler or whiter for the following reasons:

  • lack of food
  • poor water quality

Lack of Food

Make sure your plecostomus is getting plenty of nutrients and color enhancing vitamins from enriched meals focused mainly on pleco specific pellets, flakes, veggie rounds or algae wafers. Supplement their diet with the following every two days or on the weekends:

  • cucumbers
  • spinach
  • zuchini
  • kale
  • melons
  • lettuce
  • shelled peas

Water Quality

Keeping the best possible water parameters helps to bring out the best colors in your plecos along with a healthy diet. The following parameters are optimal for your plecostomus:

  • Water Temperature: 74-80° F
  • pH: 7.0-8.0
  • Alkalinity: 3-10° dKH (54 ppm to 180 ppm)
  • Nitrates: Less than 40 ppm
  • Nitrites and Ammonia: 0 ppm


Take a look at your water quality, create a meal plan, add hiding spots and enough shade to get the best colors out of your plecos. You may also wish to get a larger tank for them to have more space to swim and explore.

This way, you will decrease their odds of stress or moodiness that can also discolor or dull the colors of your plecostomus. Camouflaging to their surroundings is also a common reason why there are color changes on a plecostomus.


Thanks for visiting HelpUsFish.com for another article on plecostomus that we greatly enjoy taking care of in our aquariums. Check out more of our articles on the variety of marine life we research and keep. Bye for now!

Brian Arial

Brian Arial has kept fish for leisure and worked with fish stores for most of his life. He enjoys writing and caring for aquariums and ponds.