Are you getting the sea hare to combat hair algae? If so they work wonderful and will totally wipe out any and all hair algae in your tank in very short order. The drawback is that once the hair algae runs out the creature WILL starve to death and die within a matter of a week or so. So if you are getting it for hair algae MAKE SURE you have a place to take him after his work is finished lest it dies in your tank,spikes your nitrates and wipes out everything in your tank. If you are getting one because you think its cool or your LFS said it 'would be fine' save yourself the grief and dont buy one.