Goldfish Lying on its Side at the Bottom of the Tank: 4 Solutions

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Goldfish are probably among my favorite types of fish. That is why I tend to get worried once I see unusual behavior in their tank. For example, one time, I saw my goldfish lying on its side at the bottom of the tank. I was sure that my fish was dying. Hence, to prevent it, I began to research the phenomenon pretty extensively.

Goldfish typically lie on their side at the bottom of the tank due to a swim bladder disease, compromising their buoyancy and floating ability. However, goldfish may also sit at the bottom due to constipation, overcrowded tank, loud noises, elevated toxins, and inappropriate temperature.

As we move forward in this article, I will share a few more reasons that may cause your goldfish to lie on its side at the lower section of the tank. I will also show you what steps you should take to treat your goldfish and prevent undesirable consequences.

Why is my Goldfish Lying on Its Side at the Bottom of the Tank?

Goldfish are not bottom dwellers. It isn’t normal behavior for the fish to spend so much time at the bottom of the tank. Some people are quick to blame this behavior on ich, a disease that causes white spots to manifest all over the goldfish’s body.

That isn’t a flawed assumption to make in such situations. However, a fish with ich won’t only lie on the substrate. It will rub itself against the gravel to combat the discomfort on its skin.[1] The infected goldfish will probably not lie still at the bottom.

Things are different if you’ve noticed this behavior in goldfish covered with the white spots commonly associated with ich. You can then comfortably conclude that the disease is responsible for your goldfish’s decision to frequent the bottom of the tank.

However, if the fish is merely lying on its side at the bottom, and you haven’t identified any symptoms supporting the presence of ich, the following factors are probably to blame:

1. Swim Bladder Disease

Swim bladder disease is a symptom rather than an illness. It is concerned with the swim bladder, an organ that fish use to maintain their balance and buoyancy in the water.[2] A malfunction in the swim bladder’s operations will compromise your goldfish’s ability to control its buoyancy.

For instance, goldfish float to the top of the tank by allowing the swim bladder to fill with blood gasses.[3] If a disease or an injury has prevented the swim bladder from filling, the goldfish will remain at the bottom of the tank, unable to leave.

By using its swim bladder, your goldfish is also able to balance its head’s weight and maintain a horizontal position.[4] For that reason, if a disease involves that essential organ, your goldfish will probably find it hard to maintain straight, and choose to lie on one side.

2. Constipation

Constipation is often associated with swim bladder disease; that is to say, constipation can cause swim bladder disease. However, a goldfish can suffer from constipation without developing swim bladder disease.

But even in the absence of swim bladder disease, the discomfort and lethargy caused by constipation can immobilize a goldfish. It will eventually gravitate towards the bottom of the tank because lying on its side allows the fish to rest. It doesn’t have to exert itself.

Besides lying at the bottom on its side, a goldfish that suffers from constipation will also appear lethargic, swollen, and will feature clamped fins.[5] The condition could be secondary to various factors, although it is most likely due to overfeeding and inappropriate diet.

3. Stress

Stress has a destructive influence on most aquarium fish. It can rob them of their health and enthusiasm, forcing them into hiding or encouraging them to remain immobile at the bottom of the tank.[6] Some would say it is a survival instinct. 

If your tank is overcrowded, filled with aggressive tankmates, or poorly maintained, you can confidently conclude that your goldfish is lying at the bottom because of stress. In some situations, your fish would also be breathing heavily and rapidly.

You can expect similar behavior from starved fish and whose tank is situated in a noisy location (in the living room, for example). You should bear in mind that fish are sensitive creatures. It doesn’t take much to cause them physical and mental discomfort.

4. Overcrowded Tanks

As was noted above, overcrowding will induce stress in your goldfish. People think that fish always rush to the top when their tank is overstocked. But they are just as likely to frequent the bottom, mainly if their tankmates chose to occupy the top and middle sections. 

Fish in crowded tanks will go wherever they can find room. Sometimes, that is the bottom of the tank. Doing so allows them to stay out of sight from more aggressive fish, such as Oscars and Betta fish. Typically, I recommend sticking with more docile companions, such as Loaches and Plecos.

5. Elevated Toxins

Like most fish, goldfish are vulnerable to toxins like nitrates and chlorine. One of the most dangerous is ammonia, a substance that will burn your fish’s gills, affecting its ability to breathe. If your fish is not only lying still on its side but also gasping for air, the ammonia concentration in the water is probably too high.

That typically happens in poorly maintained and dirty tanks. Fish naturally extract ammonia from their bodies, mainly from their gills.[7] But if the water isn’t being replaced regularly, that toxin will accumulate and possibly push your goldfish to the bottom of the tank.

6. Low Water Temperature

Cold water holds more oxygen than warm water.[8] Hence, if the temperature in your tank spikes, the oxygen levels will drop, leaving your goldfish to gasp for air at the bottom. You would expect an oxygen deficiency to compel distressed goldfish to swim to the top.

However, it is worth noting that an elevation in temperature causes warm water to rise. In other words, the water left at the bottom of the aquarium is not only cooler but also more oxygenated.[9] That is why goldfish might choose to stay there rather than running to the top.

7. Disease

Goldfish are susceptible to various diseases, including flukes, velvet, and a ‘hole in the head’ disease. If left untreated, these infections and illnesses will eventually exhaust your fish.[10] Once they are sapped of their strength, the goldfish will drop to the bottom.

However, diseases and infections may also involve internal organs, such as the kidneys, liver, and swim bladder. If the latter is infected, that could directly force your goldfish to the bottom, and as mentioned, will force it to lie on its side.

How to Treat Goldfish that Lie on their Side at the Bottom?

Goldfish that lies on its side at the bottom is not always sick. Sometimes it is just sleeping. Other goldfish are old and require some rest. However, there are additional signs that suggest a more dangerous prognosis.

For example, your goldfish may also appear lethargic with clamped fins. If that is your case, these are just a few of the solutions you can pursue:

1. Improving Water Quality

Start by checking the quality of the water in your tank. Testing kits are relatively easy to find these days. The one I would highly recommend is the API Aquarium Test Kit (link to Amazon). That highly affordable bundle will measure your pH, nitrates, nitrites, and nitrates within a few minutes.

In case the pH is too low for goldfish (below 7.0), or the other toxins are too high, it would help if you performed more frequent water changes. Start with replacing 15-25% of the water weekly. After a while, you may lower it to 10-20%. 

Ensure that you measure these parameters weekly, especially when you feel that the tank is getting dirty. If the temperature is too high, I suggest investigating the heater to ensure that it is operating as required.

I will also mention that temperature fluctuations could also stress your goldfish. Ideally, the desired range for goldfish is between 68 and 74 degrees F.[11] However, the temperature should also be stable. To achieve that, I highly recommend checking the Cobalt Aquatics Neo-Therm Pro Aquarium Heater (link to Amazon).

If the summer heat is to blame for the spike in temperature, deactivate the heater. It would help if you also switched the lights in the tank off. If the temperature is still too high, you can use a fan or even ice cubes in a bag to lower it.

To overcome oxygen deficiency, I recommend adding an air stone. You can also install a more powerful filter that can create the agitation required to increase oxygen diffusion in the water. Another trick is to pour new water high above the surface.

2. Treating Swim Bladder Disease

The Youtube video above could give you a professional overview of how to treat swim bladder disease in goldfish. But if you don’t feel comfortable with such a complex approach, you could take a few other steps.

For example, if constipation is the source of this ailment, you may give your goldfish peeled peas (as in the video below).[12] You should also raise the temperature by a few degrees to improve digestion. Fasting is often encouraged in such situations. Don’t feed your goldfish for three days. 

That will give the creature’s body a chance to digest the food it already holds in its stomach. I also suggest experimenting with aquarium salt. Move your sick goldfish to a hospital tank and pour one tablespoon of aquarium salt to each gallon of water the tank contains.

Bear in mind that you cannot combat swim bladder disease without improving and maintaining the tank’s conditions. Therefore, getting an aquarium testing kit and measuring the water temperature are still essential steps.

3. Mitigating Stress

You can fight stress by eliminating negative stimuli in the goldfish’s environment. That includes removing aggressive tankmates or adding a divider. It would also be best to give your goldfish proper hiding places by adding plants, rocks, and other decorations to their tanks.

It would help if you avoided overcrowding and overstocking at all costs. Goldfish require tanks of at least 20 gallons to swim freely.[13] If you can maintain a tank with the right parameters and tankmates, stress will become a thing of the past among your goldfish.

If you feel that your tank is too crowded, please check my recommendations for aquarium kits. Besides the particular bundle that I use, I reviewed two other outstanding kits that had received hundreds of positive reviews online.

4. Treating Underlying Diseases

If your goldfish is sitting at the bottom because of a disease, the treatments you will use will depend on the disease you have identified. For instance, you can fight fungal infections with methylene blue.

With velvet, you must raise the temperature to 80 degrees F.[14] You can also use salt baths and products like Mardel CopperSafe. Anchor worms require a commercial drug that will kill the parasites in the tank.

If you have no experience with goldfish diseases, you should talk to a vet. They will identify your fish’s disease before proposing an effective treatment. You may also try products such as the API MELAFIX (link to Amazon), which are relatively commonplace and safe.

Either way, you should treat your sick goldfish in a separate tank. Besides preventing healthy fish from getting treatments they don’t need, you will also avoid diseases spreading. As a rule of thumb, it is wise to isolate every fish that seems lethargic and ill.

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If your goldfish is suffering from a swim bladder disease, it is likely to lie still at the bottom of the tank. Since constipation is one of the most common causes of a swim bladder disease, I would start by feeding your goldfish some peeled pees.

It would be best if you also took care of the water conditions. Start by testing your water for ammonia, nitrates, and nitrites. If they are too high or the pH is too low, I would suggest performing more frequent water changes. You should also vacuum the substrate and eliminate leftovers and debris.