This won't work in the tank in question, but there are larger cichlids that live in BW to marine conditions, such as Mayan cichlids (which even here in florida are sometimes are occasionally in marine), but also black belts and some tilapia species.
since i don't know how to post, I'm going to write my question here lol. I Have a 20 gallon tank and i'm wondering how many cichlids I should have in it, keep in mind i am aware they grow and I do intend on getting a bigger tank but for now they are all babies. I know having a large population of them reduces the aggression in them but I don't want to overpopulate any help is greatly appreciated.
The only brackish cichlids there are (that I know of) are green and orange chrmides. I've never seen greens on sale and they're rather drab from what i've seen, though they get a decent size and prefer fresh to low brackish water. The orange chromides are very nice but they are pretty small (max out at 10 cm) and rather weak compared to some of your fish. If you want chromides you probably will only find orange chomides. You will need another tank if you want to keep then as I doubt that they will do well with your fish.
I'm a noob, but I do have a few cichlids. They are really territorial, so I would not put them in a 20 gl, especially with any other kinds of fish. Mine went from under 2" to way over 4" in a few months, and started hurting anything else that was not there partner! I had Kenyi, JD's, Corys, and Tetras as dithers. They were relentless on the Cory's and the JD's, and the other Kenyi that were of a diff color. Took the trouble makers to a lfs, now my tank has more 'harmony'.
Alwayswantedadragon. Many cichids are territorial but there are always exeptions. I wouldn't trust any cichlid with something super delice delicate like chocolate gouramis (Which I don't own) but there are peaceful ones like german blue rams, some south american dwarf cichlids, and orange chromides. A freind of mine has a nice setup with a pair of orange chromides and a school of rummy nose tetras. Still make sure you know what you are buying and that cichlids are always most aggressive to other cichlids. even rams are mean if you crowd them.