It will fit but it's not ideal and will not eventually fill up the tank by itself. I did the same thing when I was new to the hobby....back when I thought a 55g was huge. Being in too small of a tank drove him to be an insane glass banger.
This is exactly why I suggested getting a 75 in the future. You may be able to grow out a few GTs to acquire a pair but as Tom and others have said, a 55 will not be ideal over an extended time for a breeding pair with tankmates. Since a 55 is your max it would probably be better to stock your tank with more suitably sized cichlids. There a quite a few to choose from.Although a GT could servive in a 55 for life it is not the best option or will it provide it with the best quality of life possibile, IMO I consider a 75 as the min. size for life. In your 55 I'm talking about one solo GT preferably a female unless you can find one of those Short Body GTs. Since in your orignial post you said you have no other options and no upgrading. Sun cats get too big for a 55 not even an option. A bushy nosed pleco is fine and will do a good job and about 5 corys would work too just make sure they are and will get big enough not to be eaten. A Raphael cat if provided a suitable habatat will not be see often enough to justafy the tank space or wast output. You will need to do a least weekly 50% water changes and filter with a canister such as Fluval 205/305 in conjuction with a suitable HOB. There are plenty of options for a 55 that IMO would be better. A nice EBJD would be a great option as an example. Sorry to be the guy to say it but if you followed the stocking list suggested above you would end up with a tank of stunted fish swimming in poor water conditions unless you wanted to do daily water changes but it still doesn't address the lack of space. Ultimately it is your tank and if someone says it's a great idea most people will latch onto that and disregard any information to the contrary.
Although a GT could servive in a 55 for life it is not the best option or will it provide it with the best quality of life possibile, IMO I consider a 75 as the min. size for life. In your 55 I'm talking about one solo GT preferably a female unless you can find one of those Short Body GTs. Since in your orignial post you said you have no other options and no upgrading. Sun cats get too big for a 55 not even an option. A bushy nosed pleco is fine and will do a good job and about 5 corys would work too just make sure they are and will get big enough not to be eaten. A Raphael cat if provided a suitable habatat will not be see often enough to justafy the tank space or wast output. You will need to do a least weekly 50% water changes and filter with a canister such as Fluval 205/305 in conjuction with a suitable HOB. There are plenty of options for a 55 that IMO would be better. A nice EBJD would be a great option as an example. Sorry to be the guy to say it but if you followed the stocking list suggested above you would end up with a tank of stunted fish swimming in poor water conditions unless you wanted to do daily water changes but it still doesn't address the lack of space. Ultimately it is your tank and if someone says it's a great idea most people will latch onto that and disregard any information to the contrary.
You misunderstood me I think...I didn't mean he could house his green terror with a keyhole cichlid, a firemouth cichlid, a green or gold severum, a parrot cichlid, AND A blue acara in the same tank, I meant he could house his green terror with one other cichlid that I listed and his choice of pleco/catfish. Would it be kind of crowded for 2 cichlids, and a couple of plecos? Yes, now that I think about it. & I didn't know sun catfish get that big, I always thought they got about 6-8 inches (mines stayed about 6 inches for like a year now). Now that I know they get 16-18 inches max length, a sun catfish would not work in a 55g. Also its funny you think 1 EBJD can be in a 55 for life. They get 10 inches while a GT gets 8 inches. & yes he should think about upgrading his tank to a 75 when he can especially if he gets tankmates for his GT...
i have never seen an EBJD that actually reached a full 10in and female GTs may get 8in but males definitely get 12in, GTs get larger than Jack Dempseys do and usually ebjd dont get as large as regular jacks, and yeah sun cats get quite large, what size tank are yours kept in? they should def be larger than that after a year