Mario, do you know its origination? This is an ocellate octopus (it has a pair of false eye spots, that dark circle below the eyes). The image does not give a lot of other hints but there are only two that we commonly see. The most likely is
Octopus hummelincki from the Caribbean/Gulf of Mexico. Before the 2010 earthquake, many came from Haiti or the FL Keys but we have not seen many in the years since. However, I acquired one (
ET, link to his journal) a couple of months ago from the FL Keys so I am hoping they are repopulating. The other, Octopus bimaculatus is a colder water animal from the US Pacific and, although common, is not legal to sell if caught in California. There is a third, larger animal, O. maya, that we don't see but is being raised as food in the Yucatan and have the first journal of one of these being raised in Mexico by an aquarist (
meet Itza here).
When it arrives and is acclimated look closely at the very tips of the suckers. The color is not always displayed but when it is, you should see that the very edge (not the full sucker) is either orange or bluish purple. If it is O. hummelincki, it will show the blue (from the images, it does appear that this may be the case). There is also a difference in the eye spot but the sucker outer ring color is easier to detect. If the eyespot remains brown rather than showing a blue-yellow-blue target like circle, then maybe O. maya. However, the colors of the eyespot are not often clearly displayed except during stress so a lot of observation will be needed to say with confidence. If you can determine its origination, that will add to the confidence of determining the species. All three make wonderful pets and should learn to interact during the day.