Goldfish has growing purple spot

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Skytsengel

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Can anyone tell me what this is so I can effectively treat it? I noticed the purple yesterday and it has grown larger today. That's about all I know other than this is a picture of it. Sorry for it being a bit blurry.
 

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What size tank is your goldfish in?
Do you have any other fish in the tank?
Do you know what your water parameters are?
 
125 Gallon
Yes, 4 Goldfish, 11 GloFish Tetra, 2 Hillstream Loach, 1 Albino Bristlenose Pleco, 1 Assassin Snail, no idea how many pest snails
Water quality is fine.
 
You have an interesting mix of tropicals and temperate fish there.
I asked about tank mates because some posted a picture of a flowerhorn recently, with a similar looking bruised area. It turned out it was caused by a common Pleco latching onto the unfortunate flowerhorn. I would be surprised if this marking was caused by the Bristlenose however.

How is the fish’s behaviour generally? Any other unusual symptoms? Is it’s appirite
 
It's pretty colorful and fun to watch :)

It doesn't seem to have a lack of appetite though I would say it might be a little less active than normal. Hard to tell as I only got the goldfish about a month ago, but while it use to scavenge and slurp up the 1/8" gravel and spit it out most the day, it's been kinda hovering until feeding time (best I can describe it). Best any research I have done can come up with is a microscopic parasite but I really have no idea since it's just discoloration of the skin.
 
The test I did on Saturday had near zero for Ammonia, Nitrites, and Nitrates. And I say near zero because the API master test kit I used had barely any color change from the base color. I have been testing weekly out of habit and there has never been a rise in any levels. The bacteria and plants are doing their job well.
 
Fish produce ammonia, which bacteria convert into nitrites, and more bacteria convert into nitrates, so there should always be nitrates in a cycled tank. Plants do consume some nitrates, but it needs to be a very heavily planted tank with a small amount of fish, to keep the nitrates at zero. In a healthy, cycled tank I would expect to see some rise in nitrates between partial water changes, and a drop in nitrate immediately following a partial water changes. When I see zero for ammonia, nitrite and nitrate I suspect a problem with either the test kit or how the tests are being carried out.

You have a good sized tank, but your fish are incompatible. Hillstream loaches need cool water, a strong flow and plenty of oxygen. Fancy goldfish require cool water but are not strong swimmers, so a more gentle flow would suit them. Your glofish tetra and Bristlenose Pleco are tropical and need warmer water. Some of your fish will be leaving outside of their ideal conditions, and this can lead to a weakened immune system.

I may not sure if any of these things are leading to your goldfish’s condition, but they maybe contributing factors.
 
According to researching, which I did before purchasing the fish I have, all are within the ideal temperature range of 75 degrees except the goldfish for which the water temperature is about 1 degree warmer than the ideal range. If it was more than that, I wouldn't have put them in. They swim around and seem to be getting on just fine with the temperature (just as active as they were in the LFS).

As for your concerns on the water quality, I have tested the water with the API master test kit, the local fish store, as well as a large pet store (petsmart) and all 3 tests are revealing the same thing... near zero levels of Ammonia, Nitrites, and Nitrates. The stores tested with strips, I tested with water drops from the master kit. I am fully aware of how the cycle works, have not done a single water change in four months, and yet... something is working well with my little ecosystem.

It also helps to keep in mind, NO3 weighs just over 3x as much as H2O. 60% of my plants are down in the substrate at the very bottom of the tank while the other 40% are about 5-6 inches higher up, in substrate piles on the sides of the tank. Fish waste and extra food sink and break down in the substrate and without high water flow to stir up the tank (mine is about 350 gph dissipated at the water surface), the higher concentrations of NO3 should remain in the substrate where the plant roots can slurp it up. The plants I chose (while not remembering the name of them) are primarily broad leaf plants. These were chosen thinking aquatic broad leaf plants might want more nutrients and light similar to non-aquatic broad leaf plants. I keep the lights on 10-12 hours per day and have almost no Algae, Ammonia, Nitrite, or Nitrate buildup.

This is at least my theory on why it's working well. You and many others have told me there is no way this is possible, and yet... what can I say? Here is a photo of a water test I just did about 15 minutes ago (yes, I waited 5 minutes for color to develop) and my tank. Now that we have established there is nothing wrong with the tank, are there any thoughts on what is causing the spot to develop on my one goldfish?
 

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Can you please try to get some clearer photos of the fish and the purple area? It's pretty hard to guess at a diagnosis when looking at a blur...
This is at least my theory on why it's working well. You and many others have told me there is no way this is possible, and yet... what can I say? Here is a photo of a water test I just did about 15 minutes ago (yes, I waited 5 minutes for color to develop) and my tank. Now that we have established there is nothing wrong with the tank, are there any thoughts on what is causing the spot to develop on my one goldfish?

You've admitted yourself that it's highly unusual for a cycled tank to have close to zero nitrates at all times. Especially with fish that have such a high bioload as goldfish and plecos. While you have some plants, you don't have a huge amount of fast growing plants, so it's still unusual. The nitrate test with the API master test kit is also notorious for not giving accurate results unless shaken very well before use, and a lot of people don't shake it hard enough or for long enough.

How it's working out for you, I don't know. I've never been strong with chemistry, @Essjay certainly is though. But since many people come here with a problem with their fish, and it turns out to be a water quality issue, or poor stocking, and you have an unlikely mixture of fish. I don't see why you seem annoyed that people are questioning your water test results. We can't see the tank or run tests ourselves, and can't see the problem very well in one blurry photo, so of course people are going to ask questions to rule out the most likely problems first. We need info about the tank, conditions and other fish in order to try to help. That isn't to knock your fish keeping skills. It's to check for horses before looking for zebras.

People also give up their free time to try to help others who are posting, for free, because they care. So getting annoyed at people going out of their way to try to help you seems... rude.
 
I went to the LFS and their opinion based on what I told them is some sort of fungal or parasitical infection. I am going to quarantine the goldfish and give him a one hour dip and see how it is in a few days.

As for insinuating I am rude, I posted in an emergency category and my word was not taken that the water quality was fine. By asking for results you were in a way, knocking my fish keeping skills whether you realized it or not. At the LFS, they asked me about water quality, as I would expect and I told them the same thing, that the water quality was fine. They moved on to asking if the fish was rubbing against rocks or other things and eventually landed on it sounds like a likely fungal or parasitical infection.

I am fine answering water quality questions, but time was wasted having to prove that what I said was indeed true. I find that a bit rude and thus my irritation. If I was wrong in saying it was fine and that turned out to be the cause of my fish issues, then that would be on me.

I will stop watching this thread now as the issue has hopefully been solved.

Thank you for your time.
 
As for insinuating I am rude, I posted in an emergency category and my word was not taken that the water quality was fine. By asking for results you were in a way, knocking my fish keeping skills whether you realized it or not. At the LFS, they asked me about water quality, as I would expect and I told them the same thing, that the water quality was fine. They moved on to asking if the fish was rubbing against rocks or other things and eventually landed on it sounds like a likely fungal or parasitical infection.

I wasn't the one who asked you for water quality results, so saying that I asked you and was knocking your fish keeping skills means you're taking your bad attitude out on the wrong person.

I was merely explaining WHY people ask those questions, in the hopes that you would wind your neck in and be a little more gracious and understanding. Posting one out of focus photo and expecting a diagnosis based on no further information is expecting miracles from people, while being very demanding and entitled at the same time. People frequently say that their water parameters are "fine" because dip strips are innacurate and plenty of people new to the hobby don't understand the nitrogen cycle. When they post their actual numbers, people can spot an ammonia spike, sky high nitrates from infrequent water changes, or something like a crashed cycle because the person washes their filter media under the tap. We need numbers to be able to help. Your numbers suggest a problem with your cycle. If it turns out it's somehow balanced, then fine, we move on to the next likely cause. We don't know you, your tank or your level of experience, so expecting us to be psychic is ridiculous.

It isn't a fungal infection, and since your LFS didn't know whether it's parasitic or fungal, they haven't actually resolved the issue either. You will now be medicating a fish (which is stressful for them, and lowers their immune system further) based on nothing but a guess. Then likely throwing another medication at it if the first one doesn't work. Because you are being prideful and impatient rather than actually trying to figure out what it going on with your fish. I see you did the same thing with your previous thread as you've done here, with totally different people... you're the common denominator, because you refuse to provide basic information and expect instant results.

Based on your previous post, you've had fish in this tank since early April, had several diseases, and enough losses to wipe out at least a dozen neons and 14 guppies. Since you don't list them in the current tank inhabitants, sounds as though they've all died, and you've just bought more fish. You've decided to keep tropical and coldwater fish together, because you think you know best despite being new to the hobby. You're insisting that your cycle is fine when the numbers don't make sense, ignoring the fish dropping like flies and diseases cropping up. So yes, your fishkeeping skills are certainly worth questioning.

But I will certainly not waste any more of my free time on someone who thinks they know best and refuses to listen to advice.
 
@Colin_T I know the OP has unwatched the thread and that the photo is blurry, but wondered your thoughts on what this might be? Sorta looks like damage I think?
 
If it appeared in the last few days, it is a wound or bacterial infection.
Salt and water changes should help. If it doesn't then use a medication to treat bacteria (preferably not anti-biotics).

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Try doing the following.
Wipe the inside of the glass down with a clean fish sponge.

Do a 75% water change and gravel clean the substrate every day for a week. The water changes and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in. It also removes a lot of the gunk and this means any medication can work on treating the fish instead of being wasted killing the pathogens in the gunk.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use them. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens.

Increase surface turbulence/ aeration when using salt or medications because they reduce the dissolved oxygen in the water.

Add some salt, (see directions below).

If there's no improvement after a week with daily water changes and salt, or it gets worse during that time, you will need a broad spectrum medication that treats fungus, protozoa and bacteria.

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SALT
You can add rock salt (often sold as aquarium salt) or swimming pool salt to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

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 2 heaped tablespoons per 20 litres and if there is no improvement after 48 hours, then increase it so there is a total of 4 heaped tablespoons of salt 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, Bettas & 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 (4 heaped tablespoons per 20 litres) will affect some plants and some snails. The lower dose rate (1-2 heaped tablespoons per 20 litres) will not affect fish, plants, shrimp or snails.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

When you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.
 
Looks like a festering wound to me. An ulceration of that area. I agree with @AdoraBelle Dearheart though in that this user is beyond helping. The mixture of fish itself says that... Hopefully the lovely goldfish recovered.
 

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