Octopi are very intelligent animals, so there are ethical considerations. Plus the kinds of environment they require can hamper conservation efforts
Octopus has been growing in popularity among seafood fans for a long time. 350,000 tonnes are fished, with most going to Asian countries and rising markets in Italy, Spain, and America. They're used in delicious dishes like fried calimari, grilled barbecue octopus, and pulpo gallego. To meet the rising demand, countries are researching how to raise octopus in artificial conditions. Japan is trying to open its first hatchery and Spain is building net hatcheries and large scale tanks to keep up with the public's endless appetite.
But there are some real issues with the rising demand for octopus. Farming them has real dangerous effects on the environment, in terms of the amounts of feed they need to sustain a large number of octopi for commercial purposes. If that weren't enough, octopi are some of the most intelligent creatures on the planet and there are ethical concerns about raising them in tight aquacultural pens.
Octopi have long fascinated scientists with their incredible awareness, so much so that in 2012 they were the only invertibrate added to the Cambridge Declaration on Consciousness considers sentient alongside mammals and birds. Tons of research has shown that octopi can solve complex problems (and remember the answers for months afterward) and they can recognize individual human faces. Worse, they feel pain and suffering.
Now imagine the kinds of artificial conditions that would be necessary to raise large numbers of octopi for public consumption. These intelligent animals would be hemmed in, poked, and prodded in a place where they'd go insane from stress and boredom.
Existing aquaculture depends on "tightly controlled and monotonous environments...with constant ambient conditions, simplified and sterile enclosures, and rigid feeding schedules, aimed at supporting high stocking densities." That means a lot of the octopi, which are sensitive creatures, would die of infection and would become aggressive and violent in captivity.
Add on top of this the kind of feed required to raise these creatures. Octopi are carnivorous and require lots of protein and fish oil. That would tax an already overburdened ocean ecosystem.
As the human population grows and demand for food becomes more of an issue, we have to consider how the food we consume affects the world around us. Factory farming is already such a horror show and we don't want to repeat the mistakes of our past onto our future.