If Opae'ula are Supershrimp, then I'd say red mangroves are the Superplant. lol I got all of my info about them before buying from
this site. You can safely ignore their waffle about their special mud, it's just a sales pitch. Mine I just rested on some wood, you can do the same on rocks though. They supposedly don't do quite as well on rocks as they don't soak up nutrients from the water column like wood does, but I shouldn't think slower growth would be an issue in an Opae tank.
The 3 I have I ordered pods with roots, they arrived looking like this, and I literally just placed them where I want them. They're self weighted and self righting, so no need for weights or the like. I'll post a pic of what they look like now once the tank lights come on.
The one con I can see is, they won't give your shrimp something to hide in. Oh, and you might feel a bit odd growing a plant that in Hawai'i they're trying to
eradicate from the Opae's natural habitat....
