Guam - At only eight inches long, it may seem like a small discovery but for scientists, it's a big addition to what we know about the deepest part of the ocean.

"We were in the second deepest spot in the Mariana Trench called the Serena Deep and we made a brand new discovery. It's the deepest fish ever seen and it's a fish that had never been seen - a species that had never been seen," explained Linda Tatreau.

This is the footage caught earlier this month aboard the Schmidt Ocean Institute's research vessel, Falkor. On board serving as the educational outreach coordinator was Guam's own Tatreau.

Tatreau explains that unlike most trips to the Mariana Trench, this expedition didn't go straight to the bottom - to the challenger deep - the deepest part of the ocean floor.

Instead, this expedition was intended to gather the bigger picture.

"One of the scientists on the vessel said just going to the Challenger Deep is like trying to study Mount Everest but just looking at the tip. So you've got to study the whole thing," she said.

Landers with cameras were deployed from the surface and revealed this never before seen fish.

"This one was in about five miles deep and we didn't see it until we brought the lander back up to the surface and we have the film in the control van and we looked at the film and this fish comes through and it was totally unexpected and it just kind of glides through on these fins that are like totally angelic. It's about I think eight inches long and it had a head that was kind of like a cartoon dog. Nobody had ever seen a fish that looked anything like this before," she said.

According to Tatreau, this is the deepest any fish is expected to be found. But there's still so much unknown about the deep. In fact, more people have traveled to the moon than to bottom of the Mariana Trench.

"Most scientists will tell you we know more about the surface of the moon than we do about the bottom of the ocean," she said.

At 16,000 pounds per square inch Tatreau compares the pressure below to that of ten elephants standing on top of your head.

"We know next to nothing about the Marianas Trench because you can see how hard it is to get there," she said.

To date, only three individuals have made it to the bottom.  In the 1960s, retired US Navy captain Don Walsh and late Swiss engineer Jacques Piccard made the trip and most recently in 2012, Hollywood filmmaker and explorer James Cameron.

Although it's unknown when the next manned trip to the bottom of the blue will be, it's sure to be exciting.

"We know so very little about what's down there in the trench that every expedition that ever goes finds something new - something exciting," she said.