arowana tail

Hi guys, my arowanas tail has broken it's been around 6 months I have been trying to make it grow back. I noticed that my aro's round part of the tail was broken at first and the tip of it's tail became reddish like a wound. I thought it must be parasites and used some antibiotics, general aid...

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!