I have one in my 125, moving to my 240. It needs a nice deep sandbed as it sleep in the sand [also goes there when frightened]
Great personality, great community fish. It is one of the more timid Wrasses and should not be kept with more aggressive Wrasses or similar shaped fish. I tried to put my Radiant and my Salon Fairy Wrasse [also peaceful, usually] together and the Salon Wrasse suddenly became aggressive and attacked. I moved the Salon Wrasse to my 90.
IMO, the Radiant Wrasse needs a larger tank.. They are very strong swimmers, mine is all over my 125, I could not imagine placing him in a 55
If the fish is small and you plan on upgrading, I guess you'd be fine although in a 55 I would be concerned about having 2 Wrasses, even though they are peaceful Wrasses, you don't know what will happen..I tried it with 2 peaceful Wrasses in my 125 and the one I put in last became the aggressor, he would actually bite the Radiant. This was not normal, I called the Salon Wrasse Charlie Brown, because he was the one usually being picked on...he was even scared of the Ocellaris Clowns:lol: