ok so just to be clear you want to have:
3 Os
2convicts
1 Gt
1 Jd
1 chocolate pleco
1 argentea
2 istlantum reds
1 carpintis
(just to make sure iv got your stock correctly) but yes this would probably be ok in 200g with ample filtration will be a bit crowded though so will need great deco to ensure that everyone has their own little territory so wont fight as much, of course bigger is always better and you could probably do a lyonsi with that stock if you upped to a 240 though i still think rehoming at least one of the Os would make everyone more comfortable and if your Os are a pair then i would do only 1 istlanum so that you dont have 2 breeding pairs in the same tank
3 Os
2convicts
1 Gt
1 Jd
1 chocolate pleco
1 argentea
2 istlantum reds
1 carpintis
(just to make sure iv got your stock correctly) but yes this would probably be ok in 200g with ample filtration will be a bit crowded though so will need great deco to ensure that everyone has their own little territory so wont fight as much, of course bigger is always better and you could probably do a lyonsi with that stock if you upped to a 240 though i still think rehoming at least one of the Os would make everyone more comfortable and if your Os are a pair then i would do only 1 istlanum so that you dont have 2 breeding pairs in the same tank