Goldfish Care Tips

A Free Monthly Resource For Goldfish Enthusiasts
April 2026
Issue #148

In This Issue
Swim Bladder Recovery

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Swim bladder problems are common in deep-bodied Goldfish varieties and are difficult to cure.

Most issues relate to diet and are easier to resolve compared to severe buoyancy loss, which indicates swim bladder damage.

Swim Bladder Recovery

Black Moor now swimming normally

I usually go on vacation during winter, because it is when my fish are least active, it is outside the breeding season, and two weeks without food in 10-12^oC (50-54^oF) water is hardly noticed by the fish.

I was going on vacation for two weeks in early August 2025, and I don’t like leaving heaters on.

I had four 20-month-old Moors heated at 26^oC (79^oF) to promote growth as they were undersized for their age.

I slowly lowered the water temperature over a week, far too short a time period, I now believe.

Damaged Swim Bladder

After returning in mid-August, I found the Moor in the image above struggling with negative buoyancy, suggesting swim bladder damage. He frequently gulped air at the surface, trying to inflate his swim bladder.

I also noticed he was spitting out food. This is usually an indication of damage or a blockage in the mouth or esophagus area.

I initially thought the fish had swallowed something such as a small stone that was weighing it down, but I couldn’t see anything in its mouth.

Vet appointment

After a few months of no improvement, I decided a vet visit was in order.

I asked the Vet to X-ray the fish for two reasons: to see if there was anything down the esophagus, and to see the condition of the anterior (cranial) and posterior (caudal) swim bladders. I was expecting to see one or the other collapsed.

The X-rays showed there was nothing obvious in the mouth or esophagus, and neither swim bladder was collapsed. This surprised me.

X-ray of the fish before treatment

The Treatment Plan

Because the swim bladders appeared normal on the X-ray, I assumed they had been damaged. Looking at an image in the Vet’s fish treatments manual, I saw fluid-filled swim bladders. This would make sense, as when humans get pneumonia, our lungs fill with fluid. Something similar may happen to fish when they get chilled.

My plan was to grow the fish, with the thought that by increasing its size, new tissue would be required for the larger swim bladders, possibly leading to the swim bladders repairing themselves.

I started the treatment plan by:

* slowly raising the water temperature back to 26^oC (79^oF)
* On the Vet's advice, I started a course of antibiotics in the form of a one-hour bath over seven days. This was to eliminate the possibility of a bacterial attack.
* I considered treating with Praziquantel to eliminate internal parasites, but considered them unlikely.
* I lowered the water depth to around 180mm (7 inches) to lower the pressure on the swim bladders.
* I maintained high KH, GH, and calcium levels to promote growth, adding a few tablespoons of salt to the 50-liter tank to aid buoyancy.
* Nitrates were kept low with frequent water changes, as it is believed that high nitrates constrict blood flow to the swim bladders.
* High-quality pellets and live food were fed three times a day (for some reason, he wouldn’t eat gel food).

First Indication of Improvement

In early March, the fish appeared to have better buoyancy. I thought it was my imagination at first, but gradually he developed greater buoyancy until by late March he was back to normal.

Interestingly, at the same time, he started eating normally and has shed several teeth, indicating he is growing. Whether the two problems were related, I don’t know, but I suspect they were.

I will keep him heated over Winter and slowly increase the aquarium water level to 330mm (13 inches). I will grow him out to about 100mm (4 inches) body length before attempting to remove the heater next summer.

Conclusion

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