Goldfish tail eaten?

Question
I had two smaller goldfish (I think they are butterfly tail) in a swampy area of a pond.  I recently moved them inside and noticed that the one is missing a good portion of its tail and tends to rest at a 90 degree angle (he is eating and has no other signs of disease such as spots or gasping at the surface) If there is no disease is it possible a predator got to it and will the tail grow back or does it need its own tank since the others are more aggressive?

Answer
hey ian,
he probably just got injured. as long as he isnt getting bullied, he should be fine in the tank with the others. it will grow back in time. if he is getting bullied, you will want to seperate him.

also, look into tail/fin rot. this disease eats away fish's fins, scales and tail. it probably isnt this, but double check anyway. if all of his other fins are ok, then it is most likly not this, but even if they are it could be from getting attacked by whatever hurt his tail, so its a hard way to tell. look up the symptoms and see if they match.
i hope everything goes smoothly, feel free to ask future questions. =]
best wishes, chelsey