Why Are My Guppies Gills Red? {Are They Being Poisoned?}

Generally, guppies like other fishes breathe by taking water through their mouth and releasing it through their gills. But, why are my guppies gills red?

What color should guppy fish gills be? What are the symptoms of ammonia poisoning in fish?

Let’s find out what ‘s wrong with some important details in this article below.

Why Are My Guppies Gills Red?

Red gills on guppies is caused by high levels of ammonia, nitrate or carbonate poisoning. It will also cause the gills to become swollen, making the guppy gasp for air at the water surface.

Although the gills are usually reddish because they are engorged with blood, an intense red coloration can mean something else.

Guppies Gills Red

NOTE : If your guppies gills are red you need to test the water conditions with an aquarium water testing kit (Available on Amazon) to see if there are any issues that need to be addressed.

What Causes Red Gills in Guppies?

The gills are the sensitive organ that performs a very vital function in guppies and other fishes. However, it becomes a very big course of concern when the gills become red than they usually are. You may blame ammonia toxicity for the red gills on your guppy fish.

Ammonia and carbonates are highly dangerous toxins at high concentrations. It could find its way into the aquarium from decomposing fish food, chemicals used in water treatment, organic matters and food waste.

Carbonates can as well be found in different rocks and substrates that might serve as pebbles in the aquarium.

What Color Should Guppy Fish Gills Be?

A healthy guppy fish gills are naturally a pinkish red color, They should not look a brown or silver color as this will indicate there is some sort of infection in the fish.

As the fish gets older the gills will get slightly lighter and also dryer and covered with sticky slime.

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Symptoms Of Ammonia Poisoning In Guppies

It is not a very common scenario for the ammonium level to increase suddenly. Ammonia poisoning starts when the tank’s pH levels become elevated, and consequently upsetting the nitrogen cycle.

Obvious signs of ammonium poisoning are:

  • gasping for breath at the surface of the water
  • lethargy
  • loss of appetite
  • laying at the bottom of the tank
  • bleeding spots

The gills will then develop a red or lilac colouration, making it appear like they are bleeding. The bodily function will begin to fail, making them lose appetite and becomes increasingly lethargic.

After extreme damage, the brain, organs and central nervous system become faulty. The guppy will start to hemorrhage both internally and externally, before eventually dying off.

Can Guppies Recover From Ammonia Poisoning?

Yes. Guppies can suffer gill damage from even very tiny amounts of ammonia, and excessively high levels are frequently lethal.

However, if you can identify this issue very early on and clean the water right away, the fish can live properly. Fish that have advanced illnesses or are subjected to sudden increases in ammonia levels risk dying.

Ammonia Poisoning in Aquarium Fish

Once any sign of ammonia poisoning is noticed, the first thing to do is to check out for the ammonia level in the tank.

  • If the ammonia level is above 1ppm on the standard test kit, begin treatment and tank clean up immediately. 
  • reducing the pH of the water and a 50% water change will have an instant effect that will be of great relief to the guppies.

If the damage is already intense, you can make use of a chemical pH control product to neutralize the effect.

Make sure you feed fish in small quantities and remove food not consumed in 5 minutes. Change a percentage of the water regularly and test the ammonia level in the tank at least twice in a month.

Guppy Gills Sticking Out

The most common causes of swollen gills in guppies are:

  • carbonate or ammonia toxicity.

Ammonia is a very toxic substance. Decomposing fish food, organic debris, and fish feces are the causes of it. Rake is a very sensitive organ that resembles the lungs and is greatly affected by ammonia spikes.

Why Are the Gills on My Guppies Swollen?

The fish’s gills may be harmed by excessive ammonia levels in the tank water. Fish excrement, organic materials, dead fish, and decomposing fish food all create ammonia, a very harmful toxin.

Ammonia at low concentrations can burn and expand the gills. Guppies with enlarged gills gasp for breath because of this.


Having slightly red gills can be normal for guppies, but when the red becomes intense it might mean something more. Pay attention to the pH, ammonia and carbonate level of the water once you discover the gills of your guppies are red.

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Hello, I'm Jason. I'm the guy behind HelpUsFish.com. I volunteer at my local fish shop and I created this site to offer tips and advice on the fish I care for.