Axolotl Injury

Someone please help. My axolotl is injured and I don't know why

Do you have anything in the tank he could have injured himself on?

Wipe the inside of the glass down with a clean fish sponge.

Do a 75% water change and gravel clean the substrate every day for 2 weeks.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. Wash the filter media/ materials in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the garden/ lawn.

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Axolotls had remarkable healing abilities. Keep the tank clean and it should be fine.