CA cichlids that have decent chance to not up root or destroy plants are fairly limited.
55 is a smaller tank for CA so you would want to stock smaller CA.
Probably the best choice would be a group of rainbow cichlids. More compatible with each other and probably the most plant friendly CA cichlid.
Thorichthys such as firemouth would be another option. Usually fine with plants (though not always) and sometimes works OK as a group.
Both of these don't get too large, around 6" or so.
Another option might be a female salvini. They can get to around 7" and are unlikely to bother plants much. You would need to stock it with a large number of non-cichlids in order to make it feel comfortable in the tank. Some options might be giant danios, gouramis and rainbow/red-tailed shark. A male salvini is quite a bit larger and would have greater chance of being overly aggressive. Sals probably won't do so well as a lone adult specimen, as they need a busy tank so as not to fear the surface so much. females are easily identified by the dorsal spot, even at the young age they sell them at the LFS.