The first thing you should do is find out where you read it and go back and look at the environment and be sure it was referring to O. rubescens.
O. vulgaris have been kept together raising them as a food source as well as the two caught together and displayed at Mote (this pair was found as very young juveniles and, as CaptFish mentioned, were likely siblings). The articles under the species section (
octopodidae) attached to each species may be helpful. Note that they mention a degree of predation and stipulate the tank size they used. You cannot take the information out of environment context and expect positive results.
May I ask why you would want to keep multiples in a single tank? Most interaction would be either mating, hiding from each other or cannibalism so there is little advantage to pairing them unless you want to breed. Other than O. mercatoris, most breeding experiments involve introducing the animals only for that purpose and then separating them. Going back to my
on an aquarium is not the ocean, the size tank you are considering is still a small amount of room for a single medium sized octopus, not enough for multiples and you would still need to keep it as a species tank. It would make a very nice home for a single O. vulgaris (a personal favorite) if you can locate one (not an easy task, usually an accident). Warning though, although it is at the top of my favorites list, IME this species will eat anything that moves and not on the known list of safe critters. Mine was interactive but played a bit rough (I have photos of sucker marks) where O. briareus, O. hummelincki and O. bimaculoides are gentler. CaptFish felt his (
Penelope) would attack and bite (and avoided the opportunity to confirm) if given the chance.
LittleBit wanted to play but I would not let a person without experience play with her.
El Diablo was a sweetheart but still frightened people unaccustomed to octopuses and may have outgrown his 130 gallon tank.
Have you considered keeping cuttlefish instead of an octopus? It would seem that cuttles are closer to the environment you prefer. You can keep corals (but not fish) with the cuttlesfish and could keep several in a tank that size, potentially raising hatchlings.
Look at this thread and see if it grabs your attention.