I have TONS of questions for piranha owners:

So for a couple months there's been a nearby piranha on Facebook market place for a low price. His tank (or atleast I think it's a he cuz he's pretty small) looks really small and empty, I doubt any other people in the area would really want a piranha (relitivly conservative "old people" neighborhood) and I really want to get him cuz I feel bad for him. I have never owned a piranha and it's been a while since I've had a fish at all, so I have tons of questions.

1. What size tank would he need? I've seen ALL sorts of different opinions ranging from 40-160 gallons, I've been mostly looking for 100 gallon ones but my parents are saying that would be to difficult to maintain. (And I DEFNITLY need one with a cover. I'm not sure how piranhas are likely to jump out, but I also have budgies in the same room I intes to keep the tank and I definitely don't even want to risk anything happening to them)

2. I've done some research on what tankmates would be good, and since I've learnt piranhas are really messy eaters I definitely want SOMETHING to help keep the tank clean... But I've also learnt NOTHING is a guaranteed safe tankmate for a piranha and everything is just "this will PROBABLY be fine", does anyone have any sort of plecos or snails with their piranha? What types?

3. I'd rather not feed anything live to him. I was thinking store bought shrimp would work as treats but I dunno if that would be a healthy everyday diet. does anyone know what/where to find healthy everyday food for a piranha?

Any other tips would be greatly appreciated, completely new to this... Please help me "fish police"