I'm not sure if I can say I kept them. I added them to my tank... They vanished. Then 6 months later an Eviota appeared. It was out for 3-4 days and then vanished. About a month later a Trimma appeared in a colony of xenia. Was visible for a day and then vanished again.....
Not sure if I would call it keeping. This is in a 400g tank with a bunch of fish, they can clearly live, but they aren't real visible in my tank.
Dave B