fish tails

Question
Although I have goldfish I don't believe this questions is specific to them, though perhaps it is. I have had several comit or feeder goldfish in my tank, and I find often that one will have its tail frayed then gone over the course of a few days. I am assuming that the other fish is biting its tail. My question is, is a fish able to grow back its tail, or can it survive without its tail? I hate to see it trying to survive, if it is just going to die in a few days.

Answer
Hi Jolene,
  You are correct that the most likely explanation for tail loss is by the actions of another fish, i.e., another fish bit the tail.  

 Tail fins can grow back if the damage is not too severe.  If the damage is limited to the frilly part, then that can usually grow back and sometimes rather quickly, e.g., within a few weeks.  If, however, the damage extends down into the harder parts of the tail, the bony elements that support the frilly part, then such damage is likely to be permanent.

 That said, I have had fish that were without substantial portions of their tail survive for years.  They can't swim as well, but in a tank, they don't have to swim as far or as fast as they would in the wild, and
they typically do not have to swim quickly to escape from predators.  

-- Ron
  rcoleman@cichlidresearch.com
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