Can anyone suggest what could be wrong? I have a common goldfish, pale yellow, about 10years old and about 6inches long which has developed red blotches on his head. these first appeared about 2 days ago and some sort of yellowy growth is now appearing in the centre of the blotches which are staying red. They look nothing like normal cottony wool fungal infections. they look sore but no sign of the fish rubbing them.

Can't be a coincidence that 5 days ago I added to the filter area a bagged granular product which is supposed to extract excess ammonium, nitrites and nitrates - looks like a kind of activated filter medium.

The fish is behaving quite normally and eating well. Companions in the tank - a gold one about the same size and another only 2 inches long seem OK.

Although I have had these fish for 4 years without them ever showing any signs of illhealth I have never tested the water so have no idea about ammonia etc levels.
I use filtered tap water when filling the tank and replace about 10% every couple of weeks or so if I remember. The tank is 120litres and they are feld on flake food for goldfish. There is a filter and overhead lighting; also live plants which grow well.

Hi and welcome. First thing you will need to answer all of the questions above. You will need to get the water tested, whether you get the tests yourself or have the lfs do it we need to know in order to help you. If the lfs does it write down the results so you can post them.

It could be a fungal infection. Or even a bacterial infection. Please Post back soon and we can help you further.

Hi Cmw,
The tests are important. To understand, bad water parameters cause stress, stress causes ill fish!

High ammonia can kill, Nitrite is deadly as it binds the blood cells and damages the gills and is a deadly killer also.

Even with weekly changes, one floats along on thin ice, sometimes weeks, sometimes years, then one day something goes dreadfully wrong.

Do you have any salt in the tank? Zeolites being added don't do any good as the salt will release ammonia that is bound in it, its how you re-charge it.

Salt is a good thing and a natural cure for some things, but mixed with zeolites, well, it just isn't advisable.

How big is the tank?

You can, being very careful not to get any in eye's, mouth or gills, swab the spots with hydrogen peroxide, then swab with Iodine. *_Only do this once._ *

Remove the zeolites, and any carbon media. Then, you can either do a salt treatment of 0.3% ( 1tsp per gl x 3 spread out over 3 day's so as not to shock the fish). When you change the water be sure to only add salt to the new as salt does not evaporate.

Or, get some antibiotic's (or a anti-fungus medication). One does not use Malachite Green & formalin mixed with salt either and f/mg treatments do not do well with light. The tank has to be kept dark.

The drawback with antibiotics is that like humans, fish can build up a immunity, so they should be left for a last resort if possible.

Be aware that medications can wipe out the bio bugs in a established tank too.

Do get the test kits, the water is the first thing to look at when something goes wrong.

What are you useing for a de-chlorinator?

Anything you can tell us helps as do pics as well if possible!

Can you isolate this little guy? It would be better if you can quarantine it. A high er concentration of salt will not do any live plants any favors. So you have to remove them or QT.

Thanks for the advice so far. It is 11pm here so no shops open but will get a water test kit tomorrow and post again once I have some results. Am also setting up an isolation tank for the ill fish.

Hi again Tested the water and the parameters (so far as the sensitivity of the kit allows me to identify) are as follows:
pH 7
Ammonia between 0.0 and 0.1 mg/l
Nitrite 0.1mg/l
Nitrate 75mg/l - don't need to be a genius to work out that this is way too high so have been back to the shop and got Interpet Nitrasafe which is supposed to help control nitrates. Have also changed some of the water and added Tapsafe to remove chlorine and chloramines. Finally, on the advice of the shop manager, have dosed with an anti bacterial

Did all of this about 5 hours ago. The red blotches seem a bit less 'angry' looking and more pinkish so feeling quite hopeful. Still have no idea what they are - spent ages in the shop looking thru goldfish books but none of the illustrations looks even similar. Don't have a digital camera so can't post any pictures but if you imagine a cluster of pimples, each with a blotchy red/pink base you'll get the idea.

Fingers crossed!

I am pleased to say that the 'pimple' appears to have gone! Looks like it was probably bacterial.

Thanks to Tamianth and LaurieP for your help - feel astonished at tough goldfish are to have survived with me knowing so little about them. Glad to know this site is there as it is much better than any book I have seen.

Glad to hear all is better. I must add though that the only way to reduce nitrates is thru water changes or having plants. The stuff you mentioned as well as plants may help but water changes are the only way to really control them.