The case of a goldfish with a missing fin.

[Tianna]

So I have had multiple goldfish throughout the past year. Most of them had tragically passed away soon after I put them in the tank, but two have survived. I have had them for over 6 months so they have been doing well for quite a while.

A couple weeks ago, I noticed that on one of the fish, it's pelvic (I believe) fin looked like it was just wearing away. This week had been very busy, and other than to feed them, I hadn't really had the time to really look at them. Today I got the chance to... And the fin is completely gone. I thought it could be fin rot but the Ph level of the water is correct and the tank is filtered and cleaned often.

Is this a problem that I should be doing something about? Or is it fine to just leave alone? Also, I have not seen the fish go after each other in any way.

 

[Wild West]

Try a test kit or take some of the water to a LFS to test for JUST BEFORE you clean the tank. Goldfish are notorious for for ammonia and nitrtites. Those water parameters will tell you everything, and we can guide you then too

 

[Tifftastic]

So I have had multiple goldfish throughout the past year. Most of them had tragically passed away soon after I put them in the tank, but two have survived. I have had them for over 6 months so they have been doing well for quite a while.

A couple weeks ago, I noticed that on one of the fish, it's pelvic (I believe) fin looked like it was just wearing away. This week had been very busy, and other than to feed them, I hadn't really had the time to really look at them. Today I got the chance to... And the fin is completely gone. I thought it could be fin rot but the Ph level of the water is correct and the tank is filtered and cleaned often.

Is this a problem that I should be doing something about? Or is it fine to just leave alone? Also, I have not seen the fish go after each other in any way.

I have some questions based on your post. I have bolded the things that have questions on and will list them in order.
1. a) How did you cycle the tank, or did you cycle the tank, before you put the fish in? b) How big is the tank?
2. Just a comment: goldies can live 30 years or more, six months is nothing in their life
3. a) How often do you feed them? b) I understand being busy (I'm working on a PhD, definition of busy), so I'll just ask what your normal tank maintenance is like?
4. Does the fin have like a white edge and look likes its being eaten away?
5. a) What is correct to you? b) What are the other parameters (ammonia, nitrite, nitrate)?
6. a) What kind of maintenance on your filter? b) How often is often? c) What do you mean by cleaned (partial change, full change, gravel vacuuming etc)?
7. If its fin rot, no you cannot leave it alone. The first thing I would do is take a sample of the water and test it. Secondly I would do a 30% water change to freshen the tank up. IMO the first line of defense with any problem is to keep changing water and get that as fresh as possible all the time. This will help to keep levels good which will increase the fish's immune system as it won't be focusing on dealing with nasty water.