Also, cautionary notes on handling. Octopuses are shy and not all of them are receptive to interacting, especially to touching. Some will be out front the minute you approach the tank where others will only show up when they are hungry. Very young animals (under an estimated 5 months) will almost never be seen and you have to locate their den and encourage them to eat (especially if dinner is not alive).
Always let the animal approach you, not the other way around (you can encourage by scratching on the tank or moving your fingers but don't chase). First encounters will be sampling your fingers as food items and I separate play time from feeding time. Neal prefers to play after they have a beak full of food but we have seen them shift food away from their beaks . Initially, it is usually a touch and go type contact. When they get bolder, they will latch on and try to pull you fingers to their mouth. Don't panic, gentle resistance will usually stop the initial undesired behavior but as they become more bold, you may need to stroke the back of the arms or gently (easier said than done) remove the arms using your other hand. Don't offer your hand near the live rock. This gives them a surface to grab and their strength is unexpectedly strong when they have good purchase on the substrate. It is much more difficult to disentangle yourself and your rock work will take a beating (with some animals, resetting live rock becomes a monthly routine). Some, like Monty and most hummelincki as well as the small nocturnal Macropus become gentle very quickly and like to have their mantle rubbed (or will squeeze through your fingers/hand). I think this is more like scratching an itch than enjoyment of human attention but is definitely fun for the human. Others never stop being aggressive. Little Bit (O. vulgaris) really seemed to enjoy play, always came to the front of the tank and suggested she wanted attention but was never gentle and some really seem to shun their human keepers. Each one is a unique experience.
One other thing I should always mention to new keepers that sometimes is not understood. The warm water animals only live for between 10 (dwarfs) and 18 (vulgaris) months with 12 months being the expected life span. Virtually all warm water species and most cold water animals (generally with slightly longer lifespans) are wild caught so the age is unknown and very few are less than 5 months old (likely because of the above mentioned seclusion).
Finally, I have observed that the behavior you witness for the first two weeks will not be the behavior that follows. Often an animal seems very interactive and outgoing while it is acclimating to tank life. Once it is truly acclimated (roughly 1 month) new behavior patterns appear and you will have to work with the animal regularly to have the most enjoyment of its company.
Be sure to see my notes on a few correction I suggested to your tank in the comments section, the grill for the sump/equipment area is a major concern.
Always let the animal approach you, not the other way around (you can encourage by scratching on the tank or moving your fingers but don't chase). First encounters will be sampling your fingers as food items and I separate play time from feeding time. Neal prefers to play after they have a beak full of food but we have seen them shift food away from their beaks . Initially, it is usually a touch and go type contact. When they get bolder, they will latch on and try to pull you fingers to their mouth. Don't panic, gentle resistance will usually stop the initial undesired behavior but as they become more bold, you may need to stroke the back of the arms or gently (easier said than done) remove the arms using your other hand. Don't offer your hand near the live rock. This gives them a surface to grab and their strength is unexpectedly strong when they have good purchase on the substrate. It is much more difficult to disentangle yourself and your rock work will take a beating (with some animals, resetting live rock becomes a monthly routine). Some, like Monty and most hummelincki as well as the small nocturnal Macropus become gentle very quickly and like to have their mantle rubbed (or will squeeze through your fingers/hand). I think this is more like scratching an itch than enjoyment of human attention but is definitely fun for the human. Others never stop being aggressive. Little Bit (O. vulgaris) really seemed to enjoy play, always came to the front of the tank and suggested she wanted attention but was never gentle and some really seem to shun their human keepers. Each one is a unique experience.
One other thing I should always mention to new keepers that sometimes is not understood. The warm water animals only live for between 10 (dwarfs) and 18 (vulgaris) months with 12 months being the expected life span. Virtually all warm water species and most cold water animals (generally with slightly longer lifespans) are wild caught so the age is unknown and very few are less than 5 months old (likely because of the above mentioned seclusion).
Finally, I have observed that the behavior you witness for the first two weeks will not be the behavior that follows. Often an animal seems very interactive and outgoing while it is acclimating to tank life. Once it is truly acclimated (roughly 1 month) new behavior patterns appear and you will have to work with the animal regularly to have the most enjoyment of its company.
Be sure to see my notes on a few correction I suggested to your tank in the comments section, the grill for the sump/equipment area is a major concern.