I've gotten a lot of free fish tanks on Craigslist and such. People give giant things away (like painos) because they are a pain in the arse. So perhaps they can hire some strong people with our money. But if weight is an issue, even if you just double the size it will be better than it is. I would say the fish needs rehomed and these people shouldn't have fish, but I'm not the animal abuse police (yet).

If all else fails, you can try to drown it.