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Goldfish With a Curved Spine: All Reasons & Solutions

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Over the years of fishkeeping, I’ve noticed quite a few odd phenomena. For example, there were days when I saw my goldfish lying at the bottom with a curved spine. As the years passed, I learned how to deal with that issue and prevent it from recurring. Now, I am willing to share that experience so other aquarists will get it right.

Goldfish will typically present with a curved spine due to Scoliosis, a disease that forces their back to take on an ‘S’ or ‘C’ shape. However, goldfish may also appear curved and lie at the tank’s bottom due to Tuberculosis, swim bladder disease, nitrate poisoning, and vitamin E deficiency.

As we proceed in this article, I will share a few other conditions that may force your goldfish to bend and frequent the bottom sections. I will also show you what steps you should take when this happens, including how to prevent the condition from occurring in other fish.

Why is my Goldfish Curved & Lying at the Bottom?

A curved or bent fish will lie at the tank’s bottom because its deformity prevents the creature from swimming correctly. The deformity is also a source of distress for the fish. Some fish can swim with a curved spine. Though, they tend to float at unnatural angles.

This condition may, on the other hand, completely immobilize other fish. If one or more goldfish in your tank is not only curved but also lying at the bottom, you should act quickly to identify the potential causes, which typically include:

1. Scoliosis

Curved spines and bodies are associated with several diseases. Some are more dangerous than others, with the most prominent, including Scoliosis. Of all the diseases that could cause your goldfish to curve, Scoliosis is one of the worst. 

Caused by inbreeding, hypoxia, poor tank conditions, and a Vitamin C deficiency, to mention but a few, scoliosis forces the spine to take on an ‘S’ or ‘C’ shape.[1] Scientists were also able to link that condition to genetic mutations, such as the ptk7 in Zebrafish.[2]

That condition will force your goldfish’s spine to curve since it’s a disease involving the vertebra. You may see it as the fish is born, although it mostly develops as the creature grows. It may become more prominent once the goldfish reaches maturity.

2. Tuberculosis

Like people, goldfish are susceptible to Tuberculosis. The disease is caused by Mycobacterium Marinum and does not take root overnight. It can take months and even years to develop. Once it manifests, the goldfish in question may show lethargy, scale loss, and skin inflammation. 

However, the most notable symptom is a curved spine. Fish that are relatively vulnerable to the disease are Neon Tetras, Gouramis, Black Mollies, and Anabantids.[3] Nevertheless, Tuberculosis can also manifest in goldfish and should be among your considerations.

3. Swim Bladder Disease

Swim bladder disease is the most common cause of erratic swimming behavior among fish. The ailment affects the swim bladder, an organ that fish use to control their buoyancy.[4] When the swim bladder’s health is compromised, the goldfish will lose its ability to swim normally.

If your goldfish is lying at the bottom of the tank, swim bladder disease might have robbed the creature of its ability to swim upward. The disease, which is more of a symptom than an actual illness, has been blamed on constipation, injuries, and poor tank conditions.

Some of the underlying causes responsible for the swim bladder disease may also bend your goldfish’s spine. Those include constipation, in which the fish will also appear swollen. The affected fish will also find it challenging to eat properly and will have no appetite.[5]

4. Direct Injury

A collision with the objects in the tank or violent conflicts with aggressive neighbors can cause irreversible injuries to the spine or the brain. Those will force the goldfish to take on an uncomfortable U-shape.[6]

Suppose your goldfish’s tankmates are incredibly aggressive. In that case, the creature will run to the bottom. After all, it cannot swim to the upper sections because it is afraid of the other bullies in the water.

5. Nitrate Poisoning

Aquariums have bacteria that produce nitrite from ammonia and nitrate from nitrite. Nitrates are not as dangerous as ammonia. But they can have long-lasting consequences for your fish, one of which is a bent spine. They will eventually oxidize the iron in the hemoglobin, causing Methemoglobinemia.[7]

That condition manifests when the quantity of oxygen reaching the bloodstream and tissue is deficient. Besides curved spines, nitrate poisoning is associated with fish that frequent the bottom of the tank. Overcrowding and poor tank conditions can bring about an elevation in the concentration of nitrates in the water.

6. Shock

Shock can cause a goldfish to curve and lie at the bottom. Common causes of shock in goldfish include a spike in ammonia levels, drastic shifts in temperature, and the wrong pH. You will also observe similar behavior in fish that were introduced to a new tank without proper acclimatization.

Some fish will experience shock even after being acclimatized. It takes them a while to come to terms with their new environment. The factors that cause shock in a fish can also induce stress, a condition that will make your goldfish susceptible to diseases and ailments that can curve its spine and force it to the bottom of the tank.

7. Vitamin Deficiency

Nutritional deficiencies can have dangerous side effects on a goldfish’s body, harming the liver and the kidney and assaulting the fish with ailments such as curved spines. Studies have shown that a deficiency in components like Vitamin-E can produce organ swelling, muscle fiber denaturation, necrosis, and a whole host of illnesses.[8]

The food you feed your fish matters, and a failure to meet its nutritional needs can leave the creature at the mercy of deadly diseases. It would help if you also considered scurvy, an illness that causes spinal deformity and manifests as a result of ascorbic acid deficiency.[9]

Nutritional deficiencies can occur because your goldfish are underfed, overfed, or given the wrong food items. If your fish regularly competes with other fish for food, it may lose the battle and lack the essential ingredients.

How to Treat Goldfish that are Lying Curved at the Bottom?

A curved goldfish should concern you because the deformity lower’s the creature’s quality of life. In some cases, this condition is irreversible. Hence, some fish experts will encourage you to euthanize fish with curved spines. 

But that only makes sense if you have tried and failed to treat the fish in question. Don’t be so quick to give up. Depending on the cause of your goldfish’s behavior, there are ways to undo some of the damage:

1. Adjusting the Tank Conditions

If your goldfish is curved and lying at the bottom, you should start by improving the creature’s environmental conditions. Goldfish require 25-gallon tanks, a pH of 6.5-7.5, and a temperature ranging between 65 degrees F and 75 degrees F.[10]

However, most importantly, the water temperature should remain stable. If you suspect that your tank varies in temperature, I highly recommend checking the Cobalt Aquatics Neo-Therm Pro Aquarium Heater (link to Amazon). That is the heater that I use, which I also reviewed here

Proper goldfish tanks require functional heaters and filters, not to mention air stones to prevent oxygen deficiencies. You should also perform regular water changes to keep the water clean. Add plants and decorations to provide hiding places for shocked and stressed goldfish.

2. Eliminating Toxins

To prevent spikes in toxins like ammonia, nitrates, and nitrites, you should check the water conditions quite regularly. I personally use the API Aquarium Test Kit (link to Amazon). You can find cheaper bundles or stripes, although that is the only kit that made it possible for me to perform hundreds of measures without getting a new one.

If you’ve noticed that the toxins are too high or the pH is lower than 6.5, I would recommend performing more frequent water changes (perhaps 15-25% weekly). I also suggest vacuuming the substrate, eliminating leftovers and debris.

You can prevent toxins from threatening your goldfish by avoiding overstocking and overfeeding. It would help if you also cleaned the filters to prevent them from clogging with food particles and waste that will eventually rot to produce ammonia.[11]

If you don’t have foliage in the tank, add some plants. Because they use ammonia, nitrates, and nitrites, you can trust them to lower toxins’ concentration in the tank. That is the reason why aquarists permit algae to grow in their aquariums. It keeps the waste in the water under control, to an extent.

Some stores sell products that are designed to decrease the ammonia concentration in a tank. One example is Seachem AmGuard (link to Amazon). Products of this sort are suitable for emergencies.[12] However, in the long run, you are better off performing regular water changes.

3. Feeding Your Goldfish Properly

High-quality flakes and pellets (like TetraFin Balanced Diet Goldfish Flakes and Fluval Bug Bites) are designed to give goldfish all the nutrients they need to survive. However, you are advised against maintaining a goldfish diet consisting of only flakes and pellets.

Goldfish should also consume meals that include bloodworms, ghost shrimp, brine shrimp, and diced broccoli, to mention but a few.[13] Try to give them a variety of food items. It would be best if you also fed them quantities they can consume in a minute or two.

4. Treating Disease

The treatments you will use to combat the diseases ailing your goldfish will depend on the disease. Some diseases, like Scoliosis, have no cure.[14] Hence, some aquarists will suggest euthanasia. However, it would be best if you first considered reversible conditions.

One example being Tuberculosis. You can technically attack the condition with products like rifampin, ethambutol, and tetracycline.[15] However, none of these treatments can guarantee a positive outcome. It is also worth noting that Tuberculosis is contagious. 

If one goldfish has it, the chances that it also infected its tankmates are relatively high, which is why you have to place it in quarantine the moment you observe symptoms related to Tuberculosis. Since Tuberculosis is challenging to diagnose, it would be best to isolate the curved goldfish either way.

  • Here is a good Youtube video that illustrates tuberculosis diagnosis and treatments:

Swim bladder disease isn’t as severe as Scoliosis or Tuberculosis. You can resolve it by improving the tank’s conditions, performing water changes, exposing the goldfish to a salt bath, and introducing peeled peas to the creature’s diet to alleviate constipation.

You can use a salt bath to fight a variety of diseases, including nitrate poisoning and shock. As a rule of thumb, add one tablespoon of aquarium salt to each gallon of water. Of course, you should use a separate tank for treatments.

Regardless of what you choose to do, I highly recommend consulting an aquatic veterinarian. You may take photos of the infected fish and show them to experts. You may also test the water for toxins to ensure that it isn’t the tank’s fault. 

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The reasons behind a goldfish that is lying curved at the bottom of the tank could be reversible or irreversible. One example of a disease that cannot be treated is Scoliosis, a condition that involves the fish’s vertebra.

However, before considering euthanasia, I suggest performing water tests. You should check the level of ammonia, nitrites, nitrates, and pH. Taking care of those may solve reversible causes, such as a swim bladder disease and nitrate poisoning.

Either way, once you notice a curved goldfish, make sure that you isolate the creature. That will prevent infection spreads, as might happen with Tuberculosis. I also suggest consulting an expert. An aquatic veterinarian would be a great starting point.