Red Spots On Guppy: Symptoms, Causes, Treatments & Preventions 

Guppy is among the most well-liked and friendly species you may keep in your tank. But, they are susceptible to issues including red spots.

If you have recently noticed these red spots on Guppy, you may wonder whether they harm your fish. 

It’s time to dive into this post to explore everything related to this unusual phenomenon. Let’s get started!

Symptoms Of Red Spots On Guppy

If you see red spots on your Guppy fish, it’s a sign that they may suffer health issues. 

It’s a common ailment in this species. This disease won’t be a life-threatening issue if treated promptly and correctly. 

If these aquatic creatures get infected by red spots, you may see them rubbing their skin against the tank’s rocks, walls, or plants. 

In some circumstances, this ailment may cause a decrease in appetite. What are the causes of these spots? Let’s scroll down to know!


Red Spots On Guppy: Common Causes 

Here are the main culprits causing red spots on Guppy. Let’s take a closer look!

Ammonia Spike

The ammonia spike is the most common cause of your Guppy getting a red patch and becoming red.

All of these factors might result in ammonia levels in your fish tank rising:

  • Poor water quality
  • New tank setup
  • Unregular nitrogen cycle performing
  • A high pH level
  • An overcrowded aquarium
  • Chemically treated tank water
  • Fish waste
  • An unsuitable and wrong filtration system

Your Guppy will get ammonia burns and become red if there is an ammonia increase in your aquarium.

With time, these aquatic creatures will become sluggish and lose interest in food.

Because of their damaged gills from ammonia poisoning, Guppy will typically rest near the aquarium’s bottom.

You may notice your Guppy clamp the fins and swim near the water’s surface to gasp for more oxygen.

Luckily, if you detect ammonia poisoning early, you can find and apply the right and suitable treatments to save your fish. 

Parasite & Disease

Your guppy fish’s red patches might result from an illness or parasite. If you see any moving these lines, it is evident that a parasitic bacteria is destroying the cells and fluid of your fish.

The Guppy may also have these patches on their bodies from parasite and bacterial infections. These parasites typically grow in poor-quality tank water.

Besides, the main culprit of the emergence and spread of these parasites and bacteria is contaminated water. 

Common causes

Red Spots On Guppy: Treatments & Preventions 

It’s not too challenging to treat and prevent red spots in this species. Below are the most practical solutions to apply!


Depending on the root causes, consider using one of these methods. 

Treat Ammonia Poisoning

  1. Change 50 to 60 percent of the water to lessen the ammonia level in your tank. 
  2. Stop feeding your Guppy for a couple of days to avoid high ammonia levels. 
  3. Use products to control and stabilize pH levels to reduce stress for your fish and make the ammonia concentration stable in your aquarium. 
  4. Wait until the ammonia levels decrease and reach under 0.25 ppm. During this time, avoid adding new species to your tank. 

Treat Ammonia Burning

  1. Transfer the sick Guppy into a separate tank. 
  2. Consult with an aquatic vet and apply antibacterial and antibiotic medication. 
  3. Ensure you won’t perform the treatments in your main tank because this action may eliminate beneficial bacteria.
  4. Perform a nitrogen cycle if necessary. 
  5. Apply treatment and let your fish rest for a few days (4 to 5 days) until they eat again. 
  6. After the treatment, you can move your Guppy to their main aquarium. 

Treat Parasites And Bacteria

  1. Change 50 to 60 percent of the tank water to make it clean since poor water quality is the root cause of parasites and bacteria. 
  2. Remove large parasites. 
  3. Pour aquarium salt into your Guppy tank to treat parasite infectious diseases. 
  4. Consult with a marine vet to get suitable and proper medication, depending on your fish’s condition. 



After treatments, consider the following precautions to avoid red spots on your Guppy.

Ensure you change the water at least 35 percent once a week to make the tank clean and hygienic. 

If you are unsure how to perform water changes, you can watch this video:

To keep the water free from dangerous contaminants like nitrite and ammonia, consider installing a reliable filtration system using biofilter media.

Also, add aquarium plants to your tank to clean the water and provide enough oxygenation. 

Always keep the nitrate level under 25 ppm and nitrite and ammonia levels at 0 ppm. 

Maintain the water temperature between 72°F to 82°F, and the pH level should be 6.7 and 7.8.

If you notice any of your fish get infected with these spots, the best solution is to transfer and isolate it to another tank. 



What Does Red Spots Mean On A Fish?

“Red spots” means your fish may get infected with fungi or parasites. These bacteria eat their skin, which causes lesions and deep ulcers.

How Do You Know When Guppies Are Sick?

If your fish are sick, they may show the following signs:

  • Loss of appetite
  • Listlessness
  • Weakness 
  • Loss of buoyancy control
  • Erratic swimming
  • Shimmying

Is Red Spot In Fish Contagious?

In some circumstances, these spots may transmit from sick fish to others via the tank water supply. 

Can Ick Cause Red Spots?

The answer is Yes! Ick or ich is caused by a parasite called ichthyosporidium, which is the main culprit of red ulcers or spots. 

How Do I Know If My Fish Has A Parasite?

Check these symptoms to see whether your fish have a parasite:

  • Cloudy eyes
  • Loss of appetite
  • White patches
  • Gasping for air
  • Listlessness
  • Rubbing on the tank’s wall
  • Erratic swimming
  • Redness

In A Nutshell

Red spots on Guppy may result from high ammonia spikes, parasites, and diseases caused by poor-quality water in your tank. 

You must ensure your fish tank is hygienic and maintain all water parameters properly and stability. Hopefully, this article will be helpful for you.

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