My Goldfish's tail be somewhat gone, the other fish be biting it..what do I do? ?

I had a goldfish once, and it lived with my other fish. One day, when I go to check on the fish, some of it's tail was gone. A week or so later, that fish died. A few months later, one and the same thing happened to my favorite fish. Then, another fish's tail was gone. During dinner time, the other fish be chasing that one, and biting it's tail. So, the next day I bought a separate fish tank, and put drug in that tank for broken fins, but soon, the fish died. What is going on?
Poor fish...

There's probably better answers out there if to you, but in the event that your fish's tail is rotting away there is drug out there for him/her. I personally use something called Maracyn which I purchase from Petco.

If you are certain the other fish in the tank are bullying some other fish, then the best move right very soon would be to stop mixing them together because you know the possible outcome. Make sure you are putting the same breeds together as well! I made the mistake once of not doing so, and when fish find foreign fish in the tank, they get extremely pissy...

Hope this help at least a widget =]
Fish can get fungal infections through torn fins. The best med I own found for this is called Pimafix, by Aquarium Pharmaceuticals. The other fish will go after a fish who has be beat up because they can tell he is weak. (survival of the fittest) The stress of anyone picked on can also kill them.

This medicine you can put in the container with all of the other fish, too, and it won't hurt them.
Answers:    First what OTHER fish are you keeping with your goldfish that they chase him and nip his tail?

You cannot only get a tank and dump meds and a fish in the reservoir and hope he lives. The tank still needs cycled. If your fish are being chased by fin nippers, don't hold on to the two together. If it is one goldfish chasing the other they cannot nip fins since they have no teeth.

The tank you have very soon, how long has it been up and running and how large of a cistern is it? Water changes and cleaning, are you cleaning the tank and changing out 25% of the hose? much of the water will cause the tank to start the cycle over which is more than plausible what happened to your second tank beside fish meds in it. FIn rot comes from poor water conditions. It isn't a fungus it is usually cause from bacterial infection. Simply keeping the water params in check will ward off fin rot.

Here is a site that explains the cycle and how to keep hold of the tank healthy.

Also, what are your water tests like? How something like the temperature? Really need more info here.
That's happened to my fish before, too! Does your fish own red lines on it's tail?
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