Penicillus sp. tends to go "shocky" when first introduced. They will often die way down, but leave them in place and give them a chance. As long as you have a deep enuff substrate (4" since they are true vascular plants, and not a macro algae), enuff light (they're pretty light hungry), and a mature system (at LEAST 6 mos old), they generally bounce back nicely.
HTH