Why is my Goldfish Bleeding & Turning Red? (5 Easy Solutions)

Disclosure: When you purchase something through my affiliate links, I earn a small commission. As an Amazon Associate, I earn from qualifying purchases.

I enjoy growing goldfish since they are quite hardy and can tolerate changing conditions. However, sometimes they present worrying issues. For example, there were times when I caught my goldfish bleeding, developing red patches across their body. Luckily, over the years, I learned how to deal with that issue.

Goldfish typically bleed and develop red patches due to ammonia poisoning, which burns the fish’s gills and compromises their ability to breathe. However, goldfish also tend to bleed due to mechanical injuries in the tank, and infectious diseases, including Ich, Velvet, Fin Rot, Dropsy, and Ulcers.

As we move forward, I will list a few more conditions that might have caused your goldfish to bleed. I will also present five steps that will likely improve your situation. That includes using the API Aquarium Test Kit (link to Amazon) to accurately check for ammonia spikes.

Why is my Goldfish Bleeding? (Gills, Fins, Body & Tail)

Are your goldfish bleeding? You have every reason to worry because bleeding isn’t normal for these creatures. To identify the factors causing the bleeding, you have to take several considerations into account, including the location.

The factors causing a goldfish to bleed under the scales will probably differ from the factors causing bleeding around the fins. Though, some conditions may cause bleeding in more than one location.

It would help if you also looked for additional signs such as lethargy and loss of appetite because they will enable you to narrow your long list of diseases and infections down to a small number of options. If you have chosen to take your fish to a vet, they will probably identify the following as potential causes:

1. High Ammonia Concentration

Ammonia is a common component in aquariums. It is produced when organic matter decomposes. That includes waste and leftovers. Ammonia poisoning is a common concern among aquarists because it affects the gills, compromising your fish’s breathing.

If your tank has too much ammonia, the gills may look like they are bleeding.[1] Additional symptoms include labored breathing, lethargy, and loss of appetite. If the ammonia poisoning persists, the fish will develop bloody patches across its body.

You may also notice these patches on the fins. In the worst-case scenario, the bleeding, which started on the outside, will also occur on the inside. Goldfish in such situations might eventually die.

Ammonia spikes also affect the pH, which is crucial for the fish’s well-being. The wrong pH isn’t just an inconvenience for your goldfish. It can have disastrous consequences for their health if it goes unchecked, one of which includes bleeding gills.

2. The Goldfish is Injured

This has to be your first consideration. Injuries happen in aquariums all the time. An active and excitable goldfish may collide with the sharp objects in the tank, leading to ugly bruises and tears.[2] It could also fall afoul of aggressive tankmates that may proceed to attack it, producing bloody injuries.

Injuries resulting from physical altercations or collisions with hard objects are relatively easy to identify because they don’t look like the ulcers and lacerations caused by infections. Also, the bleeding is likely to be limited to one area.

3. Your Goldfish Carries a Parasitic Diseases

Parasites are small. But unlike bacteria, they are large enough for you to see under a microscope. They are also responsible for a litany of ailments that can lead to bleeding, with the most common including:

  • Ich – Ich is a disease that causes white dots to appear all over your goldfish’s body. How does this cause bleeding? Ich causes discomfort in the fish. It will attempt to alleviate that discomfort by rubbing itself against objects in the tank. 

In doing so, it could harm itself, especially if some of the decorations in the aquarium are sharp. A fish with ich may bleed from every visible part of the body, depending on how it chooses to rub its body against the tank’s decorations. That includes the fins and scales.

  • Anchor Worms – These parasites burrow into the flesh of the fish.[3] Sometimes, this causes bleeding at the site where the worms penetrated the goldfish. Manually forcing the worm out will cause more bleeding.
  • Velvet – Caused by Amyloodium Ocellatum, velvet produces a yellow or light brown coloration that looks like a film of rust on the skin.[4] Like ich, velvet compels goldfish to scratch against hard objects. This could cause bleeding injuries. 

It is also worth noting that velvet affects the gills, causing inflammation and bleeding. Additional signs include lethargy and labored breathing. If this is the case, your goldfish is likely to swim at the tank’s upper sections, where oxygen is more abundant.

4. The Goldfish Caught a Bacterial Infection

There are so many bacterial infections that should concern you where bleeding is concerned. Keep an eye out for the following:

  • Fin Rot – Fin rot has been traced back to several bacteria, including Pseudomonas Fluorescens. Though, many aquarists blame the disease on poor tank conditions and stress. Fin rot discolors the fins, eventually causing them to fray until they fall off altogether.[5] It can affect the tail as well. Goldfish with fin rot may develop bloody patches in the affected region. The fish looks like it is bleeding in these areas.
  • Dropsy – People do not necessarily associate dropsy with bleeding. They are not wrong. Dropsy is unlikely to cause bleeding. However, along with ruining the fins, the disease may cause red spots to appear on your goldfish’s skin, which beginners may confuse with bleeding.
  • Ulcers – Ulcers are what they sound like, open sores that may cover the fish’s entire body. Ulcers have a variety of potential causes. That includes Mycobacteriosis (which leads to bleeding due to skin ulcerations), Edwardsiellosis (which also causes skin ulcerations), and Vibrio bacteria.[6] The ulcers may appear on the skin, fins, and tail. These illnesses can cause the internal organs to bleed. They are very serious.

5. Your Goldfish Has Hemorrhagic Septicemia

This disease has been traced back to Piscine Novirhabdovirus, a virus that typically infects aquatic hosts.[7] Among other symptoms, it is associated with open sores, bruised gills, and bleeding under the scales.[8] Eventually, it may lead to death.

How to Treat a Bleeding Goldfish?

If your goldfish is bleeding from the fins, gills, or under the skin, you have to match their treatment to the factors responsible for their condition. Some practical solutions include:

1. Balancing Ammonia Spikes

The best way to identify ammonia spikes is by testing the water. Personally, I use the API Aquarium Test Kit (link to Amazon). That bundle accurately measures the pH, ammonia, nitrates, and nitrites. Within minutes, it will let you know if something is wrong.

The most apparent solution to ammonia poisoning is to carry out a partial water change. If your fish requires immediate assistance, you can use water conditioners that can neutralize the ammonia within minutes, allowing you to do smaller water changes that are less likely to induce stress in your fish.

For that purpose, I usually use the Seachem Stability Fish Tank Stabilizer (link to Amazon). That product contains bacteria that work in your favor and eventually stabilize toxins such as ammonia and nitrates. This product also helps you in cycling your tank.

Don’t forget to identify the factors that caused the ammonia to spike. That includes poor hygiene (where the tank hasn’t been cleaned and organic matter like waste and leftovers have been allowed to rot in the water) and overfeeding.

Goldfish are already relatively messy creatures. If you give them food in excessive amounts, they will produce even more waste than usual, causing the ammonia levels to spike. This is why some aquarists restrict feeding when the ammonia is too high. They don’t want their tanks to accumulate any additional waste until the ammonia levels have been lowered.

2. Replacing the Water Properly

Even if your ammonia levels are appropriate, you should perform regular water changes to keep the tank clean. Doing so will prevent toxins from spiking in the future. It would also help your fish if you tested the water routinely. 

Don’t permit high ammonia, nitrate, and nitrite levels to sneak up on you. Their presence tends to weaken your fish’s immunity, making them more vulnerable to diseases. Don’t forget to apply conditioners after a water change. This will eliminate dangerous elements like chlorine, chloramine, and copper.

3. Treating Aquatic Diseases

If your fish is bleeding because of an illness, identify the condition. This will enable you to identify the appropriate treatments, for instance:

  • Acidosis – This condition occurs when the pH is too low. However, it is also problematic if the pH is too high or unstable (constantly fluctuating). One solution is to perform a water change. You can also use buffers and water conditioners to either raise or lower the pH and prevent it from crashing.
  • Fin Rot – A water change should be your first step. Clean the tank thoroughly, eliminating leftovers, waste, and any other debris. Apply some antibacterial products like Melafix (link to Amazon) where necessary. In some cases, you can treat fin rot by merely improving the conditions in the tank.
  • Dropsy – Dropsy is fatal. Besides disinfecting your aquarium with products like Monacrin, your only option is to euthanize the sick fish.
  • Ich – Raise the temperature to 86 degrees F. If it is deemed necessary, use salt baths. The easiest solution is to buy one of the many commercial products on the market that treat ich. You won’t have any difficulty finding these drugs.
  • Velvet – Besides dimming the aquarium lights and raising the temperature, you can use products like methylene blue and copper sulfate to fight velvet.[9]
  • Anchor worms – While it is possible to remove anchor worms with tweezers, the process could produce a bleeding wound, which is why you are better off using treatments like potassium permanganate, salt dips, and formalin.[10]

Infections like Mycobacteriosis and Edwardsiellosis require lab tests before they can be accurately diagnosed, at which point a vet will point you in the direction of the relevant commercial drugs. There is no guarantee that the antibiotics you have will produce positive results. You need a lab test to identify the best drugs to combat such conditions.

4. Treating and Preventing Injuries

Keep hard objects with sharp edges out of the tank to prevent your goldfish from accidentally cutting themselves. It would be best to keep the creatures with suitable tankmates such as Zebra Danios and Platies, which are unlikely to harm them.

If your fish is already injured, you can use antibiotics like erythromycin and minocycline to prevent infections. Some aquarists use Epsom Salt (link to Amazon). If you choose salt, pour four teaspoons for each gallon of water.[11] I suggest doing so in a separate tank.

5. Improving the Aquarium Conditions

Maintain the appropriate conditions in the tank. Buy a testing kit and use it regularly to ensure that the pH, temperature, and hardness are accurate. Do not keep your goldfish in less than 20 gallons of water.[12] Like most fish, they hate small, cramped tanks. More importantly, small tanks require a lot of maintenance because toxins accumulate very quickly.

Can Goldfish Heal Themselves?

Goldfish can heal themselves. They can even regrow body parts like tails, fins, and scales. Like humans, they have mechanisms that can heal wounds, grow new cells, form new tissue, and combat infections. Naturally, the healing process depends on the injury, and in some cases, can take months.

As an aquarist, you can assist the healing process by placing the goldfish in a hospital tank with all the appropriate parameters. You are also expected to keep it on a nutritional diet. Using salt may enhance healing and prevent further infections.


If you noticed that your goldfish is bleeding, first test the water parameters. The most crucial factor in this equation is ammonia. If it is too high, it might have burned your goldfish’s gills. That can end up with external and internal bleeding.

However, if the parameters are correct, direct collisions can be the cause. Make sure you remove sharp objects that can cut your fish. You should also consult an aquatic veterinarian to rule out an infection. To be safe, isolate the bleeding goldfish to prevent potential spreads.


  1. https://www.thesprucepets.com/ammonia-poisoning-1378479
  2. https://be.chewy.com/aquarium-fish-injuries/
  3. https://www.petassure.com/new-newsletters/seven-parasites-harmful-to-your-tropical-fish/
  4. https://www.liveaquaria.com/article/84/?aid=84
  5. https://www.thesprucepets.com/fin-rot-1378481
  6. https://www.msdvetmanual.com/all-other-pets/fish/disorders-and-diseases-of-fish
  7. https://en.wikipedia.org/wiki/Novirhabdovirus
  8. https://goldfish-emergency.com/Forum/goldfish-bleeding-beneath-scales/
  9. https://www.hartz.com/common-fish-ailments/
  10. https://modestfish.com/fish-disease-guide/
  11. https://www.algone.com/using-salt-in-the-freshwater-aquarium
  12. https://www.aqueon.com/information/care-sheets/goldfish