Nice! Polys are always good. Sens grow pretty quickly. Mine has grown 2 inches a month since I got it at 2 inches (currently 6). It should do just fine for line in the 55 w/ those fish.
Mine grew pretty quick to about eight inches and now has slowed except to get fatter. Nice little pick up. I almost impulse bought a couple of albino sens the other day, along with several other fish.
he is a cutie.. they are so neat..love the way they chew and throw the pellets around and then have to go find them.. tape up all the little open spaces.. they love to roam.. lol good luck with him..your going to love him! i bought two..one grew and one didn't.. mutt and jeff ..get along great and also have rope fish with them.. they are all buddies.
''do they really prefer to live in groups?'' Well they will usually tolerate each other I have kept them together and singularly and never really noticed a difference in behavior-Anne