Hi. I'm new to this forum because I'm considering setting up a tank for an octopus. I've read around a little bit and found some basic information about care- I ran across this site because it came up frequently in my google searches. It looks great! But let me cut to the chase: My dad and I have two tanks set up at our house- one reef tank, and a predator tank with two morays. We got a 30 gallon Oceanic BioCube a while ago, and we just started to think about an octopus. From everything else I've read, 50 gallons seems to be the minimum cut-off- so my main question is whether or not I could still effectively keep a cephalapod (and nothing else, really) in it. What I have learned so far are a few things about salinity sensitivity and a considerable maturation time for the water. It also seems that the reccommended species is bimaculoides, preferably tank bred. It seems that adequate filtration and surface area for gas exchange may not be easily acheived with a BioCube- given especially that it would be wise to have a protein skimmer as well. Just wondering what your thoughts were, and whether my suspicions about a smaller tank might be true.