Goldfish Septicemia: What Is It And How To Treat It

Goldfish, one of the most popular and common freshwater aquarium fish. When they are kept in an indoor aquarium, they stay at approximately one to two inches in length. If you move them into a larger aquarium, they will get bigger but will peak at about six inches. Goldfish can become victims of illnesses, diseases, and bacterial infections like Septicemia, just like any other fish.

Septicemia is caused by a bacteria called Aeromonas. When these bacterial pathogens enter your goldfish’s system, it often results in septic shock. The initial signs of Septicemia are red streaks that will turn into lesions. Your affected fish should be moved to a separate aquarium. The vet will give them a broad-spectrum antibiotic. 

Be mindful, the broad-spectrum antibiotic may or may not work. To keep your fish from contracting Septicemia you need to keep your goldfish healthy by providing them with well-oxygenated, clean water. 

Septicemia can be contracted in many different ways and can be treated in a variety of ways. These are things we are going to cover in the text today. We will also give you more signs and symptoms of the infection, how they contracted it, how to treat it.

Remember what I always say; educate yourself on everything freshwater aquarium-related. You also want to dedicate time to learning all there is to know about the fish you want to keep in the tank. Knowing all you can about your fish, will help you catch Septicemia and other problems a lot sooner.

What Is Goldfish Septicemia?

Goldfish produce a large amount of metabolic waste, including ammonia. You need to make sure that you have a filtration system that is biologically, chemically, and mechanically strong enough to handle this. It will help keep some disease and infection away and will keep your goldfish happy and stress-free.

Septicemia, or sepsis, is a clinical name for blood poisoning. Both animals, including fish, and humans can contract sepsis. This is our body’s response to an infection. The infection is located in the bloodstream. 

If your fish become injured you need to double your water changes. Keeping the wound clean will help keep them from contracting Septicemia.

Septicemia is a life-threatening condition whether you get it or your goldfish acquires it. The body’s response to infection will cause injury to its own organs and tissues.

After this stage, there will be immune system suppression. Sepsis warrants immediate treatment or it can be fatal. Septicemia in fish can occur when an open injury gets infected or they can contract it from eating bacteria in their food. 

How Do Goldfish Get Septicemia?

Goldfish and other freshwater aquarium fish can become sick because of many different things. This is one of the main reasons why you need to know everything there is to know about keeping fish as pets. Educate yourself on filtration systems, the species of fish you want, and the foods that are best for them. 

Goldfish can get Septicemia from many different situations. It can occur because of an injury, stress, overcrowding in the tank, dirty water, contaminated food, or the side effects of another illness such as fin rot. It can be transmitted by infected fish or an ammonia spike in your aquarium.

Overcrowding of your aquarium is one way to lose a large number of fish if it is contracted from another fish in the tank. Too much ammonia will cause stress to the immune system of the goldfish. This causes them to become too weak to fight off the life-threatening microorganisms.

When these bacteria enter your goldfish’s system it travels through their body very quickly. This will cause damage to body tissue, blood vessels, and the heart. Sometimes it will result in internal bleeding.

What Are The Signs Of Septicemia?

Septicemia has a couple of different warning signs. Again, a great reason to educate yourself on the fish species you plan on keeping in the tank. Then you know when something is not right or if your fish looks “off” or different. Diagnosis will be confirmed by a culture of the disease organisms from the goldfish. 

If your goldfish has Septicemia you are going to notice some hemorrhaging and ulcers on different areas of the body. There will also be red streaks on his body. The ulcers will develop into open wounds which will destroy the skin and underlying tissue of the goldfish.

As the infection spreads, fluid will build up in the abdomen. In turn, the skin of the fish will turn red or purple, in places. His mouth and fins will also hemorrhage as the skin color diminishes.

Eventually, the liver, heart, and kidneys will fail. If there is too much ammonia in the water, then your fish should show signs of breathing problems; hyperventilating, rapid breathing, swimming rapidly, or coming to the surface often. Too much ammonia leads to severe oxygen depletion.

How To Treat Septicemia In Goldfish 

If your fish seems sick or you see any of the signs of Septicemia, you need to call the pet store or your veterinarian immediately. Then you need to set up a separate hospital, tank, and move the infected fish. Hopefully, you have caught it quick enough that your other fish do not become infected. 

The first thing, the only thing that may cure your goldfish, antibiotics. There is also medicated fish food; Anti-Bacteria Medicated Fish Food. You can also soak fish pellets in a mixture of Mardel’s Maracyn & Maracyn 2. Soak the pellets for about 10 minutes, adding a few drops of water.

You want your infected fish in a separate tank so that the antibiotic doesn’t destroy the good bacteria in the tank. The antibiotic used to treat Septicemia is usually designed to dissolve in the water. This makes them easily absorbed by the goldfish. 


There is no guarantee that any treatment for Septicemia is going to work. A lot of it is going to depend on how severe the sepsis is. If it was not caught and diagnosed early enough, then, unfortunately, your goldfish is not going to survive. 

Keeping your aquarium clean, your filtration system in tip-top shape, your fish in a large enough tank is a good start to avoiding illness in your aquarium. Make sure you buy your fish at a very reputable pet store, as not to bring home any infections or diseases.

Keeping goldfish, and other freshwater fish, stress-free will also aid in keeping away unwanted illnesses. When your fish are stressed then their immune system is compromised. 

As always, I can not stress enough, the need to educate yourself on everything about freshwater aquariums, the equipment that you need, and the fish that you are wanting to keep in the tank. It will save you so much guesswork and hassle in the long run when trying to diagnose a problem with your fish or even your tank.

Having the perfect water temperature, filtration system, pH, and food will keep your fish happy and healthy. 


I'm passionate about fish pets and love sharing everything I learn about them.

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