Way over stocked.
Silver Dollars like to be in groups 6+
Oscars get to be 12-14 inches long... That's a lot of fish and needs a lot of room. Also very territorial Firemouth
is also very territorial.
Convict is extremely territorial as well.
Striped Raphael wouldnt be worth the bio room it would take up in a tank like this. You would probably need to see it if it has a hiding place, if it doesn't it will be severally stressed.
If you are heart set on the Oscar
you should pick that and something else MAX (this is pushing it and tbh an Oscar
should be alone in a 75). Depending on what you pick you might be able to get more.
For example you can do an Oscar
and one other medium sized cichlid (Firemouth
/convict) and be pushing it... Or you could probably get by with an Oscar
, a school of top water dwellers (wont swim in the same tank space is nice too to fill up space and no territory issues) and a cleaning crew and get by with it.
All of this is assuming your cichlid (if you pick one) is tolerate of other fish and you have enough filtration to cover it.