Why Is My Goldfish Turning Red? Top 4 Common Reasons!

As a fishkeeper, tons of questions will bombard your mind once you spot some red patches on your goldfish, both on its body and fin. This may indicate some health issues requiring urgent treatment for their well-being.

So, why is my goldfish turning red? 

Ammonia burns may be the root cause. Beyond that, subpar water conditions can exacerbate the red pests’ development. But the water quality itself is not potent enough to trigger the weird signs on your fish. 

Our writing will discuss more reasons, feasible treatments, and prevention tips for this situation. We’ll spill the tea!

Goldfish Is Turning Red

Why Is My Goldfish Turning Red: 4 Popular Root Causes

Four reasons that your pet turns red include high ammonia concentration, injuries, parasitic diseases, and bacterial infection.

1. Parasitic Diseases

Parasites are tiny. But unlike bacteria, they’re large enough to be visible under a microscope. They cause a litany of bleeding-causing diseases, including:

  • Ich: It leads to white spots on a goldfish’s body and creates discomfort. They will rub against tank objects to feel better and may hurt themselves if aquarium ornaments are sharp. Fish with ich may bleed from every visible body part, like scales and fins. 
  • Anchor Worms: They will burrow into the fish’s flesh. Sometimes, this results in bleeding where the worms puncture the fish.
  • Velvet: It stems from Amyloodinium Ocellatum and develops light brown or yellow spots looking like rust on the fish’s skin. Like Ich, it stimulates the animal to scratch against hard things to feel more at ease and end up bleeding.

Also, Velvet triggers inflammation and bleeds off the gills. Lethargy and hard breathing in fish are other symptoms in this case. Hence, a fish with velvet will swim at the tank’s top, where oxygen is abundant.

2. Seriously Injured

couple of goldfish

Aquatic injuries are common. Excited goldfish may clash with sharp tank objects, bringing tears and bruises. Not to mention, aggressive tank mates may attack your goldfish, causing gory injuries.

It’s easy to figure out the collisions and physical altercations caused by sharp objects. They never look like lacerations and ulcers due to infections.

3. High Ammonia Concentration

Almost no aquariums are free of ammonia. It’s created when organic matter decays. It comprises waste and leftovers, ruining poisoning fish gills and limiting their ability to breathe. Too much ammonia may cause the gills to look like they are bleeding.

Other symptoms may be lethargy, heavy breathing, and appetite loss. Once the fish gets the serious poison, multiple red spots will pop up on the fish’s whole body. 

In the worst scenario, the bleeding occurs outside and inside the fish’s body, and your fish will die.

To explain, ammonia surges impact pH, severely affecting the fish’s health and killing it.

High Ammonia Concentration

4. Bacterial Infection

Bleeding stemming from bacterial infections is another possibility. Watch out for some sure signs:

  • Fin Rot: It is caused by Pseudomonas Fluorescens. But many aquarists blame inadequate tank conditions and stress. Fin rot discolors the fins, which will then tear and fall off. It can affect the tail as well. Fish with fin rot will emerge with bleeding patches on their bodies. 
  • Dropsy: It is unlikely to create bleeding. The condition can only leave red spots on your goldfish’s skin, which beginners may mistake for bleeding.
  • Ulcers: They are open sores covering a fish’s whole body. It may derive from many reasons, including Mycobacteriosis, Edwardsiellosis, and Vibrio bacteria. Some parts of the fish, like skin, fins, and tail, are vulnerable to ulcers. More than that, these illnesses can hemorrhage internal organs and kill the fish.

How To Treat a Bleeding Goldfish?

1. Boost The Aquarium Quality

It’s recommended to purchase a testing kit to check temperature, pH, and hardness. Also, goldfish require at least 20 gallons of water. 

Like most fish, they despise cramped and small living spaces. Remember to keep tanks frequently cleaned since pollutants build up quickly.

2. Prevent & Treat Injuries

Keep sharp objects out of your goldfish’s tank to halt injury. It’s a good idea to add Zebra Danios and Platies into the tank as they’re safe tankmates for the critters.

For injured fish, antibiotics like erythromycin and minocycline can push back infections. Moreover, Epsom Salt does wonders in this case. Four tablespoons of salt per gallon of water are suitable.

3. Treat Aquatic Diseases

Identifying the reason for a bleeding fish will help you come up with proper therapies, such as:

  • Acidosis: Low pH is the top reason. Too high or unstable pH is also a hazard. To this end, you’d better change the water. Alternatively, use water conditioners and buffers to raise or lower pH and minimize the fish’s discomfort.
  • Fin rot: First things first, change the water. Empty the tank and eliminate all debris, leftovers, and garbage. It’s better to add the antimicrobial Melafix to your tank as well. 
  • Dropsy: Aside from cleaning your tank with specific products like Monacrin, euthanize all the ill fish.
  • Ich: Heat the tank to 86 degrees F. If needed, utilize salt baths. Also, the easiest solution is to acquire an Ich treatment. 
  • Velvet: You can deal with velvet by dimming the aquarium lights and boosting the tank’s temperature. Employing copper sulfate and methylene blue also does the trick.
  • Anchor worms: Do not use tweezers to remove them, as it worsens the matter. Instead, use potassium permanganate, salt dips, or formalin to tackle the worms.

4. Replace The Water The Right Way

Replace The Water The Right Way

Even if ammonia levels are acceptable, do regular water changes to clean the tank. This way, poisons won’t rise high in the future. Test the water often to foster your fish’s well-being as well.

Don’t let ammonia, nitrate, and nitrite levels slip up. Their presence weakens fish immunity, making them more disease-prone. Also, use conditioners after each water change, as they will get rid of copper, chlorine, and chloramine.


Why is my goldfish turning red? Now you should grasp the all-rounded answer. When your goldfish bleeds, checking the water is the top priority. 

It’s paid to remove sharp objects that can harm the fish. A veterinarian can rule out an infection. Remember that to avoid spread, isolate the bleeding goldfish.