I'll point you in a direction and not use too many words to do it:
What does "really bad luck" in this instance mean?
Can you provide a clearer image? It's difficult to tell if those are growths or holes or something else.
Did that fish look as it does when you got it?
How long have you had it?
Yes, there's something wrong with its fins. They s/b uniform and pretty as opposed to torn up and ugly.
Are there no other tank inhabitants or is it that you think no other inhabitants are bullies?
Is there something with a sharp edge near the top of the tank or on the underside of the lid?
Black Arowana are unusually delicate when young and that one looks very. Do you have experience keeping delicate fish or is the Aro your first?
Do you hear that fish startle and jump once in a while? Is there a predator tank very near this tank by chance?
Based on the quality of the pic it's hard to be certain but assuming I'm reading the shadowing correctly that fish may be really hungry. If you're feeding it a lot and it's not growing that could be an indicator.
As young as that fish appears to be you may find that there's more bad luck on the horizon.
There is a lot of expertise on this forum and you're in the right place. I've had several black and a couple silver Arowana over the last few decades and others here have far more experience than I. I have a 2' long black aro now.