Hi Az, could you give us a few more details?

1. How big is your tank:  Gal / litres

2. For how long has the tank been set up:

3. How many fish:

4. What kinf of fish:

5. What are the water parameters:    Ammonia.........ppm
                                                            Nitrite..............ppm
                                                            Nitrate.............ppm
                                                            pH..........................
                                                            Temp...............degrees Celsius / Fahrenheit

6. How often do you perform water changes:

7. How big are your waterchanges:      .....................%

8. What kind of waterconditioner are you using:

9. Do you add beneficial bacteria:

10. Symptoms your fish is showing:

11. Since when does your fish show these symptoms:   

12. How is the normal behaviour of your fish:

13. How do the other fish behave:

14. Post pics of the sick fish:

15. Do you have a filter on your tank, what kind, how big (gallons per hour)

16. Do you provide extra aeration with an air pump and air stone/diffuser of some kind.




Please remember: the more detailed information you can give, the better help we can provide.

Don't have a test kit? Get a sample of water to your pet store ASAP and then post the numerical results.

Ah hiya, thanks for answering the questions

I'm not entirely sure what the pimple is in all honesty, when did you last clean your filters? Perhaps rinsing the media in some old tank water, checking any pipe work for a build up of gunk, just make sure everything's clean.

As you have a lot of fish in that one tank (it is slightly over stocked, how long is your current tank in inches?), I would possibly consider doing larger water changes, it's great that you do one every week, but perhaps try doing more 50 - 80%, it'll help keep your nitrate down as that is a little high (you definitely don't want it going over 40ppm).

I've been looking around online and all I can seem to find is that it might be either a wart or abscesses, which could have been caused by bacteria.

I did come across this forum post, which may be helpful to you as it has suggestions for treating abscesses in the second post down, perhaps do some research and see if an abscesse meets what you're seeing;  (Link is not visible to guests. Please register to view.)

How is the fish doing? Any other changes physically or behaviourally that could help indicate what's happening?

Aww that's great to hear about the bigger tank Just keep in mind another upgrade might be needed, depending on how quickly the fish grow Generally my way of telling if a fish needs an upgrade, is judging by the size of the fish and the size of the tank.

So one stocking rule is that you want a tank to be 6x the length of the fish (I find this rule works well for goldfish). So for an adult goldfish this would be a minimum length of 6 foot, but with your fish being a lot smaller currently I think something 4 or 5 foot would do for now You can then decide later whether you want to up the tank size (it'd have to be something at least 6 foot, to support the goldfish's growth as they never stop growing) or build/find a pond.

I'm in a similar situation as my goldfish is very little (probably a similar size to yours) so I have her in a 90L/3 foot tank, but as she is by herself, water quality and stocking isn't an issue, but once she's around 6 inches (which is roughly 1/2 a foot), I'll be upgrading her to a larger tank or a pond (which is where single tailed fish really belong).

Definitely seems like lack of cleaning could have been the cause of the pimple, I can only imagine the mess you came home to! My one goldfish makes a huge mess by herself, so I can only imagine what 4 of them would do!
Glad to hear your fish is getting better though