I have an 11 year old common goldfish and he has recently been having some swimming issues-but only in deep water after a few hours. He is fine in shallow water and he can swim fine for about 8-9 hours in his tank but any longer that that and he ends up on his side or swimming in a spiral pattern. Once this happens he will recover in a few hours once he is put in the shallow water. He seems fine otherwise-eating etc. normally and all water parameters are normal for a freshwater tank. He has been to the vet and on x-ray there was some increased density in the bones of the respiratory tract and they suspect that a bacterial infection is the cause, but the vet was unsure of why this would cause swimming problems. He is currently on a course of antibiotics and anti-inflammatory medications from the vet to try and help him. I am just wondering if anyone has any experience with this sort of presentation?

  • how deep is the deep water are you talking about several meters or only a few cm,has your fish problems in changing how deep is swim as in problems going to the surface when you feed it. Commented Jun 27, 2020 at 7:33
  • He is fine swimming in about 15cm deep water but in his tank the lowest the water can be with the filter running properly is 30cm and he can’t sustain swimming in this depth for long-he does fine in it for a few hours and then seems to get tired and ends up on his side again
    – Katie
    Commented Jun 27, 2020 at 11:33

1 Answer 1


I do not think the swimming problem is related to the increased bone density so you need to take a look at other possible causes, it sounds to me like this might have a neurological cause like nerve damage.

Swimming normally for several hours before the symptoms begin is a bit strange, had it been swimbladder problems it should have been a constant problem.

Increased bone density in the respiratory organs of goldfish can have several causes, one is low oxygen. Over time this is often a result of living in water that is too hot; if the temperature is above 25 °C water can hold little dissolved gases - this causes the gills to work harder to keep the oxygen level up and the heart has to work harder too.

If a fish has swimbladder problems it will change the buoyancy of the fish, it will float or sink; this causes the fish to have a jerky swim pattern where it struggles to maintain its possition in the water.

Swimbladder problems can be caused by a viral or bacterial infection in the lining of the swimbladder or the tube leading to the swimbladder, internal deformities in the swimbladder or the tube leading to it can be the reason for chronic swimbladder problems.

A fish tipping over or laying upside down is not the same as swimbladder problems. This is often caused by neurological problems, probable causes for this is infection of the nerves or the brain, another cause is poisoning by nitrite-nicotine-insecticides or air fresheners in the room if inside. Outside pesticides might be the cause, CO2 poisoning can be a cause for this too.

The most common cause for problems in a fishtank is overfeeding, or that the tank is not properly cycled before fish are introduced to the tank.

  • 1
    Thanks for the reply! The increased bone density was the only abnormal finding from the x-ray, the swim bladder showed no signs of infection/deformity. I don’t think the water quality would be the cause either as the water parameters are always ammonia and nitrites at 0, nitrates at 5-10ppm and pH at 7.4. The water temperature is 20-21 Celsius. I am always extremely careful with changing the water and not using any chemicals near the tank so I can’t think of anything that would have caused this. The tank was cycled fully before he was in the tank 1year ago. I don’t believe he is overfed either
    – Katie
    Commented Jun 27, 2020 at 12:00
  • @Katie it sounds to me like you have the knowledge about fish and water chemistry and know how to make fish thrive,i have to be honest and say this is a mystery to me i have had fish in fish tanks and in ponds for a very long time and i find your problem with the goldfish strange i realy hope this can be solved by one of the users on our site. Commented Jun 27, 2020 at 14:41
  • I’ve always tried my best to make sure I keep the water in the best condition for him! I’m not really sure either it seems really strange, the closet thing I’ve come across that seems to have similar symptoms to my common is whirling disease. I’m not sure if this is actually common in goldfish but I’ve read others saying they have experienced it, and also am unsure of how he could have contracted the parasite as there’s been no new editions to the tank, I think I’ll ask my vet about it as a possibility anyway. Thanks again for your help!
    – Katie
    Commented Jun 27, 2020 at 19:42

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