I saw this come up in a different thread, and I think it's worth discussing. Seeing as I've kept 3 octopuses, I think I should chime in with my experiences. Using RO/DI water is a must with octos. They will not tolerate any sort of pollutants in the water. They're fairly tolerant of nitrate from what I've read. If you have SPS corals growing in your water, it's probably OK for an octopus. I used Instant Ocean salt for my saltwater. I don't know if other brands will work, but IO definitely does.
As far as species go, O. bimaculatus and O. bimaculoides or "bimacs" are by far the hardiest, cheapest, and most readily available octos, although they will quickly outgrow a nano. The min tank size for these guys is around 30 gallons. I ordered mine from www.fishsupply.com . A lot of online sites can get an octopus, but they have no idea what species it is. Fishsupply can positively ID bimacs, and they collect in an area (West Coast) that not many other octos inhabit anyway. The downside is that these guys prefer a cooler water temp than most reefs can handle. I kept one at 77, but it was not very happy. I believe the NRCC breeds them at around 65. 70 is a good compromise, but not a very good temp for corals at all.
The species that would probably be best for a nano is one of the pygmy octos. They usually come from the Caribbean waters and can tolerate reef temps. They stay small and are quite secretive in general.
The downsides with any octo are the inability to keep most other inverts with them, and their propensity to escape. All motile inverts (and verts) besides echinoderms and bristleworms are likely to become lunch. I suppose a tank could be cleaned by bristleworms, brittlestars, and urchins though. Sealing the tank from escape is a must. I actually kept a ping pong sized bimac in my refugium for 3 months w/o a top. For some reason bimacs won't try and crawl out of a tank unless very stressed out. All other octos are a different story. They can and will squeeze through very tiny holes to escape. I've seen video of a giant octopus with a wingspan of 6 feet or so squeeze through a hole the size of a fist, so you can imagine what the small ones can do.
There is much, much more information on cephalopods at "The Cephalopod Page"
As far as species go, O. bimaculatus and O. bimaculoides or "bimacs" are by far the hardiest, cheapest, and most readily available octos, although they will quickly outgrow a nano. The min tank size for these guys is around 30 gallons. I ordered mine from www.fishsupply.com . A lot of online sites can get an octopus, but they have no idea what species it is. Fishsupply can positively ID bimacs, and they collect in an area (West Coast) that not many other octos inhabit anyway. The downside is that these guys prefer a cooler water temp than most reefs can handle. I kept one at 77, but it was not very happy. I believe the NRCC breeds them at around 65. 70 is a good compromise, but not a very good temp for corals at all.
The species that would probably be best for a nano is one of the pygmy octos. They usually come from the Caribbean waters and can tolerate reef temps. They stay small and are quite secretive in general.
The downsides with any octo are the inability to keep most other inverts with them, and their propensity to escape. All motile inverts (and verts) besides echinoderms and bristleworms are likely to become lunch. I suppose a tank could be cleaned by bristleworms, brittlestars, and urchins though. Sealing the tank from escape is a must. I actually kept a ping pong sized bimac in my refugium for 3 months w/o a top. For some reason bimacs won't try and crawl out of a tank unless very stressed out. All other octos are a different story. They can and will squeeze through very tiny holes to escape. I've seen video of a giant octopus with a wingspan of 6 feet or so squeeze through a hole the size of a fist, so you can imagine what the small ones can do.
There is much, much more information on cephalopods at "The Cephalopod Page"
