arowana tail cut

Hi All, 1st post and looking for help here. I moved my arowana into a new tank which has been cycling for nearly a month before I added the aro in. After 2 weeks, I noticed his fins were shredded. For your info- the aro is alone in the tank. water parameters read as follow from API test kit...

I got this arowana yesterday! It's a RED TAIL GOLDEN! In the evening I observed it's tail cutting off from the fleshy part! And finally at night it broke off, but now more part of the tail is starting to separate! What might be the cause and would it grow back! THANK YOU!