Yes, I'm fully aware of how big the marine betta gets (I'm a masters in biology concentrated in marine sciences). I bought the betta when it was a baby (less than an inch in size), but they are an extremely slow growing fish. I do plan on transferring him out of that tank when he becomes too large of size, as for a 200 gallon for that fish would be a bit of an overkill on tank size (although I'm sure he would love it). As of now, he is doing excellent and is very interesting to watch. The purple reef lobster can and will work in a 14 gallon bio cube. Also as I said before, their is the possibility that they could be agressive and go after smaller fish, but their is also the possibility that they could be nonaggressive and not bother any fish. It is all in what the aquarist is willing to risk and try. As for my purple reef lobster, he worked out great for me, doesn't bother anything or any of the inhabitants, is visible almost constantly, and I think is quite awesome; but that is a test tank and I was willing to take the risk so I thought I would share my personal experience with it.