Won't the aro outgrow the oscar?The only complications I see are one fish out growing the rest (oscar), food aggression/competition (oscar most likely) and minor aggressions but besides that everything else is ok until you put them in the 7 foot tank.
Sent from my SCH-R830C
Funny how diff fish are individually+1 clarius cats are evil the aros fins won't even get chance to grow back once they start bullying the tank , I had to get rid of my 12" one because of fighting with a jardini and pretty much every other tankmate it came across