Hi there, and welcome to FnF!

Congrats on your new goldfish! I would strongly suggest, though, that you get a larger tank. Goldfish need at least 10 gallons each (they put out a lot of ammonia, which is toxic to them, and a common/comet/generic goldfish will grow to around a foot).

There's lots more info in our Goldfish Care Sheet, and more detailed stuff in our Goldfish FAQ.

I'm glad you did a 100% water change, as this tank will probably need daily 100% changes until you can get a larger tank. Even a large, never-seen-soap tupperware-like container (I've seen them in 20+ gallons at hardware stores) would work in the interim if you liked. Cheap tanks can often be found at garage sales, in classifieds, or through your local freecycle or craigslist.

You may want to invest in a water conditioner -- this will remove chlorine, but also chloramines and toxic heavy metals from the water.

It does sound like she has some ammonia poisoning, which is possibly from the pet store, but could also be from the tank she's currently in.

Fish produce ammonia and expel it via their gills (whereas we combine two ammonia's and pee it out as less toxic urea). It causes burns (like what you're seeing on the tips of the fins), hemorrhages, stunting of growth, decreased immune function, etc. In a larger tank, with a filter, bacteria start to build up that eat up this ammonia, and convert it into another chemical called nitrite. Nitrites are no less toxic though, but more bacteria build up and conver them to nitrAtes, which are less toxic and removeable by water changes (usually 25% water and gravel cleaning weekly in a cycled tank).

Right now, I would do another partial or full water change with same temperature, conditioned (if possible) water. As well, I would suggest feeding very lightly (even feeding every other day) for now, and removing uneaten food from the tank (as it can also cause ammonia build-up).

As well, can you check for velvet dusting (a flashlight can help)? External parasites can also cause some of the behaviour that you're describing.


I know this is a lot of info, and may conflict with other things you've heard -- so, please, feel free to ask any and all questions that you may have. We're here to help.


~Ash