The Goliath tiger fish is said to grow up to 150 pounds (68 kilograms) and has terrifyingly long teeth.  It swims the tumultuous Congo River, the second longest river in Africa (after the Nile) and exemplifies some of the extreme biodiversity in those waters.

The freshwater elephant fish, on the other hand, uses it's long trunk-like snout to sift through river bottom sediments for food. Like the Goliath Tiger Fish, it too swims the Congo River.

With it's soft, transparent head, the Pacific Barreleye (Macropinna microstoma) fish shows off its highly sensitive, barrel-like eyes topped by green orbs. Humans have known of the deep-sea fish since 1939, but only from badly mangled specimens dragged to the surface in nets. This is a photo (at right) of the first intact specimen of the fish, which measures 6 inches (15 centimeters) long. It was discovered and photographed alive in the deep water off California's central coast by the Monterey Bay Aquarium Research Institute (MBARI) using a remote submersible.

Tentatively named "Psychedelica," this new species of frogfish is covered in elaborate yellow and peach stripes from it's blue eyes to its curved and off-center tail. Its fins have evolved into something sort of like legs, which it uses to bounce along the sea floor like a fist-sized rubber ball. The fish was discovered last year by SCUBA diving instructors working for a tour company in Indonenia. They contacted Ted Pietsch, lead author of a paper published in this month's edition of the journal Copeia. Pietsch submitted DNA work that identified the fish as a brand new species.

This giant stingray, weighing an estimated 550 to 990 pounds (250 to 450 kilograms) was caught and released on January 28, 2009, as part of a National Geographic expedition in Thailand. The stingray's body measured 6.6 feet (2 meters) wide by 6.9 feet (2.1) meters long minus the tail, making it one really big fish. It is currently the largest freshwater fish on record, worldwide.

Octopi have tremendous intelligence, and several other qualities as well. "Octopuses have a wonderful combination of intelligence, tremendous manipulative ability, curiosity, and strength," said Jennifer Mather, a psychology professor at Canada's University of Lethbridge who studies cognition in octopuses. Octopuses demonstrate behavior that suggests curiosity, consciousness, and even a sense of humor. In one instance, an octopus given a slightly spoiled shrimp stuffed it down the drain while glaring at its keeper through the glass of its tank.

Recently at the Santa Monica Pier Aquarium in California a foot-long (0.3 meter) female California two-spotted octopus swam to the top of her tank, disassembled a valve, and released at least 200 gallons (757 liters) of seawater into nearby exhibits and offices. The octopus remained unharmed in her tank, but the aquarium's brand-new floors were less fortunate. For people familiar with octopus ingenuity, this will come as no surprise.

This tiny fish has tiny fangs that have earned it the name Danionella dracula, and it has now been recognized as a newly-discovered species! Researchers at London's Natural History Museum discovered several specimens of the Dracula fish in a tank of other aquarium fish. The tiny fish measure only 0.7-inches long (1.7-centimeters). The fish don't actually have true teeth, meaning that they don't have an enamel exterior and a pulpy center. Instead, these are bony extensions of the jaw. Scientists think that the fish use their fangs for fighting with rivals and looking ferocious, rather than for eating.

Seahorses are some of the most enchanting and mysterious creatures in the ocean. They are also in trouble, struggling to survive in threatened habitats around the world—coral reefs, sea grass beds and mangrove forests. That’s why it’s so important that we tell their story—and make a difference for their survival.

The new Secret Lives of Seahorses exhibit at the Monterey Bay Aquarium includes West Australian and zebra-snout seahorses, ribboned pipehorses, bluestripe pipefish and yellow-banded pipefish. The fabulous new exhibit gives visitors a chance to come face to face with these fascinating little creatures, explore their mystifying behaviors and unusual adaptations, and learn about their fragile habitats.