Sorry, I just got my message and came to this thread, (it's been a busy past few days). You could do a Peacock Mantis (O. Scyllarus) in the 29 gal., that is the minimum. You can only keep one per tank, they are very territorial creatures. The only way you could have two is if you had a mated pair, and that is next to impossible. If I am correct, I believe Dr. Roy has only successfully done this once.
You would definitely need a sand bed, and a pretty good depth at that. They use the rocks for their home, but they use the sand to burrow. The rocks are more or less top cover and some side cover, they they mainly burrow. Jawdubb was right about being able to use pvc piping, but you can only use pvc piping with a sand bed. They are like premanufactured homes for the mantis. I personally think that the mantis should work to build there home without pvc, plus it helps to simulate a natural habitat as well.
As far as the wrasse goes, as long as it is a top dweller, then it may have a pretty good shot at survival. Any bottom dwellers, have a severely lowered survival rate. This only goes for smashers though, which a Peacock is. As Jawdubb said, no fish would survive with a spearer, but you don't have to worry about that.
He will be with a orange back wrasse but I will get rid of him if I get the mantis. So what kind of care do they need? What would be a good type thats not to needy?
