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Anna, Pet Expert/Biologist
Category: Pet
Satisfied Customers: 11061
Experience:  40 yrs.: herps, pocket pets, rabbits, poultry, dogs, horses. Biology degree. Vet assistant.
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I have seven goldfish that I adopted 4 years ago from a small

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I have seven goldfish that I adopted 4 years ago from a small glass tank. I put them in an outdoor pond and they have grown double their size.(originally eight, though one died, suspect murder from the alpha of the group!) However, no other issues until now. The fish have a pump with mesh filter, and a water plant as well. I try and change water at least once a week and clean filter. Refilling has always been from hose as they seem to like the flow of water and seem to wash in it. As it is filling, I add a 2 in 1 pond water conditioner. Recently the two 'fatter' species have been displaying loss of colour and are looking pale. One is also displaying white blister like formations on head and body (they actually look like a blister). All fish are not floating on top at all unless they are eating, they are getting a combination of 3 different goldfish food (flakes, pellets and granules) at different times, though only are fed once a day, sometimes twice depending on weather. Scales and fins look ok (to my untrained eye). I must admit, I do not own a water tester. I have been flying off uneducated guessing until now! The pond does have algae on sides, but that has been there for a while. Any suggestions re the blisters and paleness?

My name is XXXXX XXXXX I would like to help you today. I am a biologist and have over 30 years experience keeping fish and ponds. I apologize that no one has responded to your question sooner. Different experts come online at various times. I just came online and saw your question. I'm sorry to hear your fish are having a problem. If you still need help, some additional information will be useful.

How many liters/gallons doe your pond hold?

How long are the fish from mouth to tip of tail?

Do the blister-like growths actually look like they contain fluid or pus?

If it's possible for you to test the water (some pet stores will do it for you), give me the numbers in parts per million (ppm) for ammonia and nitrites?

Look closely at the fish. Do any have red streaks or spots on the fins or tail?

Thank you.


Customer: replied 3 years ago.

Hi Anna, thank you for responding. i tried to upload a photo of fish, however, not working. Pond is about 100litres or so. Fish in question is about 7 to 8 inches. Looking at photos I took, the white blister does not look infected ie, pusy or weepy. It looks like what our skin looks like if I had a band aid on for a while and took it off. Meaning that the skin had paled whilst under the plaster. Does that make sense? I did not see any other issues with scales or tale. The fish has a bump under skin around the what might be equivalent to a human shaolder blade, but no discolouration. The water I tested was around the nuetral/akaline colour I think from reading the colour about 7.3 from the tesing kit I purchased. Again, I see no signs of distress or the same formations on other fish. Only one other has started to lose orange colour on head to white, but no 'blister' type signs. let me know if I can help in any other way.

Cheers Amanda

Thank you for getting back to me, Amanda.

Did you test the water for ammonia and nitrites?

Do the white blistered areas look at all like this photo?



We are dealing with quite a time zone difference between where you live and where I do in the central United States, and that will lead to some delays in responding to each other. We can just work around that.



Customer: replied 3 years ago.

C:\Users\Quaz\AppData\Local\Microsoft\Windows\Temporary Internet Files\Low\Content.IE5\E2AY8AHZ\Outlook[1].zip

Customer: replied 3 years ago.

sorry I do not know how to show you the photos, do not know what I am doing wrong!. Do you actually have an email address I could attach to? The photo you showed me does not really look like what my fish has, however, as an untrained eye, I am unsure!. Apologies. Any suggestions on how to upload to the website? Cheers Amanda

Thank you for trying to send a photo. JustAnswer policy doesn't permit contact between experts and customers off the site, so I can't give you my email. Here's what you can try:

Click on REPLY, then at the top of the area where you would type is a tool bar with icons. Click on the little paper clip icon (it's right next to the YouTube icon). Instructions will pop up. On some browsers, this doesn't work. if that happens, you can put your photo on one of the free photo sharing websites, such as Then come back here and paste the link to your picture in a REPLY.

Were you able to get ammonia and nitrite results? The pH is fine, and in this situation, it doesn't really matter anyway.


Customer: replied 3 years ago.

Download 097.JPG (1045.3 KB)

Customer: replied 3 years ago.

Hi Anna, I appreciate your patience. I have emailed four photos for you to the said address. 3 are of the fish in question and one is the pond without the filter on. In one of the pitures you may be able to see the lump under skin as stated. The rest are mainly of the white mark on fish head. Please let me know if I can assist in any other way.


Thanks again,


I'll watch for the photos, and get back to you as soon as I receive them.

The photos came through. Thank you. Before we go on, I do have a question about one of the photos. It is a back view of the fish. It looks like long white strings are trailing from his fins and tail. Is that real, or is one of those weird things happen with underwater photography?

Once I know that, i'll be able to answer your question.

Customer: replied 3 years ago.

Hi Anna, the white streaks were reflective, not on fish! Cheers

Thank you. Judging from the photos, I believe the fish with the blister-like growths has contracted carp pox. Carp pox is caused by a virus in the herpesvirus family. Koi and goldfish can get it. The growths behave erratically. Some will disappear. New ones may show up. They change sizes. sometimes they all disappear, only to return later. There is no cure for it, but the affected fish seem to live healthy normal lives with it. It is believed that most goldfish have been exposed to it, but have built up a resistance to it so they don't become infected. If they are stressed, an outbreak can occur. It first shows up in pond fish most often in the spring and fall, when temperatures are changing. Your other fish won't catch it from this one, but any of them could grow these lesions at any time, since almost all carry the virus.

As for the color change, it may be normal. Many goldfish change colors as they get older, usually becoming paler. I've seen both orange and black fish turn completely white. However, if the fish stop eating, become lethargic, have drooping fins, or any other symptoms, then they may be ill. Stress can also cause fish to become pale. However, we can't treat them for any disease unless real disease symptoms appear. I would keep an eye on them and if anything else seems abnormal, let me know in a REPLY, and we'll go from there. Even after you rate this answer, you can always come back to this question to reply, and I'll be happy to address related follow-up questions at no additional fee.

As for the algae on the sides, that poses no threat at all to your fish. It sounds like you do a wonderful job of caring for them. Since carp pox can't be treated, and pale color may or may not mean anything, I don't recommend any treatment at this point. Just monitor the fish for any changes. If you have more questions about this, let me know by clicking on REPLY.


My goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back, I am happy to address follow-up questions. Please remember to rate my service once you have all the information you need. Thank you!

Customer: replied 3 years ago.

Hi Anna, thank you again, I forgot to ask about water changing and filter cleans. I perhaps change half or more of water once a fortnight or so (more often when it is hot), would this be to much, even with a water conditioner? Also. should i be mixing up their food a bit? I read that vegetables such as peas were good? What do you think? thanks again

You're welcome. Your water changes are not too often, and if your fish stay healthy, that schedule is all right. However, it is usually better to do smaller water changes more often, for example, 10% to 25% once a week. Variety in diet is always good. Fish that live in ponds often find some variety as insects and amphibian eggs end up in the water. You can try some produce and see if they like it. It is good for them.

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Customer: replied 3 years ago.

Hi Anna, thank you again for your advise. The fish in question seems to be going OK. The white mark that initially concerned me has almost dissapated, however he has another one close by. This one has seemed to have shunk over the last week or so. I am now looking very closely at all fish, I seem to be more paranoid about any differences now! I have taken your advise and will certainly be in touch if it gets the better of me! Thank you again.


Hello Amanda,

You're welcome. Shrinking, disappearing and new ones showing up is typical of carp pox. The growths can be white, pink, or the same color as the fish. Thank you for the update.


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