I've had both in my tank for almost 5 years.And,they are all the originals I dropped in.The scarlets are probably the better of the to.They seem more docile than the blues.The blues are more agressive and crawl on everything.But try to remember that crabs are opportunists,and will always be on the look out for a meal.They will eat snails if they can't get enough of something else.I have always been confused as to why it is said to add ton of hermit crabs to a new tank.I know you need a cleanup crew,but when they run out of food....I hope I don't stir something up by saying that.It is just my opinion.I have always added just 1 crab per 5gal. on a new tank.Anyway,I would look for the scarlets first.:yes: