New Tank - Compatibility Questions

[The_Desacrator]

So I am on the verge of getting a 60 gal tank, and I'd like to know if I could get this line up of fish. I know the general minimum for Oscars is ~55 so I was hoping to squeeze in a couple of other fellas. I asked a similair question ahile ago and the feeback I got was that 2 convicts(not paired) with a single oscar could do fine. Can convicts be kept alone?
1 Tiger Oscar
1 Convict Cichlid
1 Parrot Cichlid

 

[HUKIT]

Thats pushing it to far in my opinion, a single oscar is pushing the limits of good water quality in a 60 but with another large fish like a parrot is way over the top. Not to mention any aggression issues from the oscar.

Oscars are prone to HLLE which is caused by poor diet and water conditions. Even a single oscar can foul the water quickly causing high nitrate levels which lead to the disease. Even with a oscar and lets say your female convicts your going to have 1-2 weekly water changes of 40-50% to keep nitrates at a acceptable level of 20ppm.

 

[The_Desacrator]

How bout the same in a 75gal? I used aqadvisor and it seems that these fish and that size tank would do ok.