PHOTOGRAPH: COURTESY OF GEORGE MAVRAKIS

What should people know if they’re considering the leap from fresh to salt water?

Fresh water is a lot more forgiving, and people tend to have success fairly easily — just let the plants grow, let them go rogue in a glass box of fresh water. Salt water is not that way. Coral needs attention every day.

What makes it so difficult?

It’s just fixing problem after problem after problem. Coral will die within a few hours if your water parameters aren’t right. But when you see it thriving, it’s the best feeling ever. Then you start trading your corals with other hobbyists. It’s like FarmVille.

What saltwater fish do you recommend for a beginner?

The clownfish. It’s hardy, and it’s peaceful — it can coexist with a lot of other different types of fish. It swims out in the open; it doesn’t hide. It’ll eat anything. And it doesn’t require a lot of territory, because in the wild, it sticks to one spot on a reef.

You don’t usually think of fish as having territory. How much do they typically need?

About three to four gallons per fish. So if you have a 20-gallon tank, you don’t want to do more than four-ish fish. Keep in mind, when you add all the sand and rock, the true water volume might only be 17 or 18 gallons.

What’s the hardest fish?

There are certain fish and animals that will inspire you to get into the hobby, but you’re not ready for them right away. Seahorses you have to feed a few times a day. Jellyfish are difficult. There’s a fish called the mandarin goby — you need to feed it a very specific type of live food. A lot of people have no idea, and it dies. The octopus is like master level. I’ve been keeping saltwater aquariums for more than 10 years, and it took me that long to even think about getting one. They need pristine water, and they require a lot of stimulation so they don’t get bored and escape.

How do you entertain an octopus?

You give it live food — crabs, snails, little fish — and toys. You can throw Legos in there. It’s like a baby.

In one of your most viewed videos, your octopus did escape.

We got it in Florida. I had been looking for one for a very, very long time, and I wanted it to be from the right place. I didn’t want them to ship it because octopuses will ink when they get scared, and if they don’t escape, it can kill them. So that’s why we took it with us on the airplane. But midflight, it inked. We had to take it out of the container, and it was crawling all over the bathroom.