Own-tail biting?

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I have not seen or been aware of that with fish.
However, in live small mammal collections (mostly colonies kept for research, such as rats, possums, rabbits, dogs, foxes, ferrets and others), it is relatively common to have individuals who will chew and even eat an own extremity (leg, tail, or so). This is usually in animals kept in individual cages, and has been interpreted as "boredom", "frustration", or "who knows", rather than hunger or anything like that. Clearly points to very sad keeping conditions.
 
I've had a convict with streamers so long that he could see them when he turned around, so he'd spin around for a bit trying to catch them. He was never able to cause damage to himself though, definitely not to the same degree as your situation, but tail or fin chasing isn't exactly unheard of.
 
F FJB : "Clearly points to very sad keeping conditions"
My thought too but I really hope not. I'd kind'a break my heart as we put a lot of effort into these fishs' well-being including enrichment. This one is in an >8' 230gal with surface plants/structure & a good deal of flow, for example.
 
My apologies. I did not mean your fish or your tank. At all. I have no idea, and very much doubt that would be the case with you. I was referring to the poor mammals in cages eating their own tails and legs.
 
Never heard of this in a fish before. Out of curiosity, I did a little research and found a few similar reports, but not many. Found two threads in MFK that mention it directly - Arowana tail biting and my arowana's tail is broken. They aren't too conclusive as to the cause or the fix though. On other forums as well, people observe it but can't figure out what to do about it. A lot of people start by suggesting external parasite treatments, but the treatments don't seem to solve the problem.

I would tend to agree with FJB above - it sounds like a fishy analogue to what mammals do when stressed. Often the stress is due to difficult living conditions, but even well- cared for animals can become stressed. For example, I've heard of sound-sensitive dogs in apartments that harm themselves due to background sounds that their owners can't even hear. In that vein, perhaps try checking the aquarium for stray voltage, and for malfunctioning equipment in general.

Some people mention that their arowana started biting itself after it got spooked. I used to have a wolf fish that would hide for two weeks if I banged the lid too loudly, so that sounds like a reasonable possibility. Perhaps you could try turning the lights off for a few days and just leaving the fish alone. Maybe it will start feeling secure again, if that's what it is. Tough one to figure out. Good luck with it.
 
Arowana in extreme stress, tend to bite their own tail.

This happened to one of gold head bluebase xbacks, this happened right after a series of events,
He was being grown out in a 50 gallon, at 5", he got finrot, and i thought the irregular water temps of the tank must've caused this and i moved him to a 220 gallon, although fin rot went away, he started being really skittish in the large tank.

So I moved him into a 120 gallon that is in my living room, as the tail started to heal he started to bite his tail, and used to always stay in a corner and stopped eating.

It took me a long time to slowly get him to even eat regularly, it only accepted once in a while small quantities of soft foods for nearly 3 months or so, he used to get well, his tail used to heal and suddenly again he would bite his tail, after a while he stopped that as well and i moved him into a comm tank with 2 young reds and larger 24k xb and a batik, that's when I saw him recuperate and start behaving normally again.
 
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