Axolotl attacking his tail

[Spytma]

Hello everyone. I have 2 axolotls that live in separate tanks. Every once and a while I come home and the larger one has a chunk taken out of his tail. Considering he is alone in the tank and I do not find pieces of his tail I can only assume he is attacking his own tail. Normally I don't worry about it but this time it is bad. What can I do to prevent this?

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[Petersgirl]

Hmm...I've never heard of an axolot attacking himself, but that doesn't mean it can't happen. Is there anything he may be catching himself on? Any chance he could have caught it in a filter or on a sharp edge? (Even commercially available hides that seem safe can have sharp edges - our log had a few and we had to sand them down before our boy could have it).