we have been keeping saltwater and freshwater fish for several years and thinking about trying to get an octopus for a 20 gallon tank (specimen tank). what special requirements do octopus need, including food, equipment, and water quality?
If you're still at the thinking stage, it's usually wise to go bigger for octo tanks, we generally recommend 55gal for the octos that make the best pets. There dwarf species that could do well in a smaller (and we suggest 29gal minimum anyway) tend to be shy, nocturnal, and reclusive, while bimacs, briareus, aculeatus, and hummelincki get big enough that they tend to do better in large tanks. The biggest concern is that they produce a whole lot of waste, and they're very sensitive to water quality, so it's much safer to have a large water volume so that any problems can be corrected before they get critical. Of course, they also like to be able to move around, too.
Anyway, the home page is in a state of flux, but there used to be an ARTICLES tag at the top... but now the articles are just on the main home page www.tonmo.com for the moment... take a look at the equipment list, bimac care sheet, and similar articles there to get an overview.