I use wild Ilyanassa in my tank. They last for many years. I don't even acclimate them- I just toss them in. Since they are intertidal, they are used to extremes in temperature. At this time of year they will do well. They don't transfer as well in early spring when local temperatures are still low, although sometimes they respond to the warmer temperatures by laying eggs all over the place. Don't bother with the hermits...they look great, are very active, and are far more entertaining than the usual blue and red legged that we keep. But they don't live long in a tropical system. As someone else posted, 6 months tops. I have kept them longer when I had a cool "local" invert tank. Temperatures there were allowed to drop into the low 60's, even 50's in winter, and salinity was way lower...1.017.