Why is my fish swimming in circles?

[Okay]

Three days ago, I added a platy to my tank of one Molly fish. I've had the Molly fish for four months, but I've never seen him swim in circles. Two days ago, he started swimming in circles every few minutes (twirling). I had hopes that he was just playing around, but since he's been doing it for two days now, I'm concerned. I checked the water quality and everything seemed to be fine. I don't believe it's ich because neither of the fish have white spots. I also don't think that he has swim bladder disease because he swims normally other than the whirling. Could it be stress? They are in a small-ish tank (I hope to move them to a thirty gallon soon). Again, he is twirling every few minutes. The platy fish doesn't twirl at all.

Am I just overreacting?

 

[Fishmanic]

I would put him in quarantine. I had a tetra that had that issue and he soon died.

I found this response on another site and will quote it here. Whether you want to rely on this information is up to you though the original poster does sound knowledgeable. I personally am not an expert on this.

"I'm so very sorry to give you bad news.Whirling disease is caused by Myxobolus cerebralis, a parasite. These parasites infest the tissues around the inner ear and the brain, interfering with balance mechanisms. Some fish that get it will twirl in circles. Some will float head down. Others may develop a bent spine. Emaciation commonly occurs in most fish that are affected as the infection progresses. Whirling disease has become fairly common in koi, goldfish, and tropical fish. It is thought to be carried in tubifex worms and possibly other similar foods, whether live or freeze-dried, but of course in a pond, it could have been brought in through many different organisms. It is most often fatal.

You'll need to make a decision. Most people euthanize fish when they begin to exhibit whirling.

If you don't want to euthanize, there are still two choices. The affected fish do need to be removed from the pond. If they die in your pond, millions of the little parasites will be released from their bodies almost immediately upon death. That greatly increases the chances of more fish being infested. You could put them in a big RubberMaid tote or a child's plastic wading pool with a filter running, and simply wait for them to pass away. Rarely, a fish will seem to recover, but that fish will always carry the parasites.

The other option is to try to treat the fish. It is only rarely successful, but there have been cases of a cure. Treatment has to be carried out for an extended time, usually about 3 months. Not all fish respond to it. Only one drug has been found to ever work: kanamycin. You can either place the fish in a hospital tank (a large RubberMaid tote works). You can also treat the entire pond, but that does get expensive. While here in the States we can buy this drug in pet stores and online, in the UK it is only available by prescription from a vet.

It can be combined with Furan 2 and Metronidazole for stubborn bacterial infections. Whirling disease is stubborn, so you may want to consider this."

 

[Colin_T]

Hi and welcome to the forum

When fish start to spiral or swim around in circles, it is caused by a bacterial or protozoan infection in the brain. These are normally caused by dirty environmental conditions (dirty gravel, filter and lack of water changes).

Do a 75% water change and gravel clean the substrate each day for a week.

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Add salt to the tank now and with every water change for the next couple of weeks.

You can add rock salt (often sold as aquarium salt), sea salt or swimming pool salt to the aquarium at the dose rate of 2 heaped tablespoon per 20 litres of water.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 4 heaped tablespoons per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria but the higher dose rate will affect some plants. The lower dose rate will not affect plants.

After you use salt and the fish have recovered, you do a 10% water change each day for a week. Then do a 20% water change each day for a week. Then you can do bigger water changes after that.