Swordtail

Wild Swordtails are found from southern Mexico and down to Guatemala in Central America. The name Swordtail is derived from the body of the male Swordtail. The bottom ray of his caudal fin is extended, and points out from the body like a sword. The female Swordtail is without sword, and she can also be distinguished from the male by her more rounded body shape. Today you choose between red, black, green, albino and even neon coloured Swordtails since Swordtails have been extensively bred in captivity during many years. You can also choose between a lot of different Swordtail types, such as the Red Simpson, the Spotted Swordtail, the Gold tux Swordtail and the fanciful Lyretail.

Danionella dracula

One of the evolutionary peculiarities of my favorite lab animal, the zebrafish, and of cypriniform fishes in general, is that they lack teeth. They lost them over 50 million years ago, and don't even form a dental lamina in development. So this photo of a cypriniform, Danionella dracula, gave me a bit of a start beyond just the nice fangs and the ghoulish name.
The story doesn't give much detail, but I'm going to have to look into this. Those are not true teeth, but spiny outgrowths of bone directly from the jaws.

Ghostshark (hydrolagus melanophasma)

A new ghostshark species has been identified off the coast of Southern California, and

it’s darker and weirder than any shark we know.

The purplish black ancient relative of the modern shark comes packed with a suite of odd features that give its taxonomical family the name chimaera, after the mythical beast made from the parts of many animals.

“It’s a big weird looking freaky thing,” said ichthyologist Doug Long of the California Academy of Sciences. “They have some shark characteristics and they have some that are very non-shark.”

Perhaps the most intriguing feature of the newly described species, Hydrolagus melanophasma, is a presumed sexual organ that extends from its forehead called a tentaculum.

“They have this club on the top of their head with spikes. People think it’s used for mating,” Long said. “It’s like a little mace with little spikes and hooks and it fits into their forehead. It’s jointed and it comes out. We’re not sure if it is used to stimulate the female or hold the female closer.”

Fish That Can Live on Land

Australia has long battled with all sorts of harmful, invasive species--and wildlife authorities are concerned that they may soon be facing a new threat from what may be one of meanest-looking of unwelcome guests. The culprit is a particularly troublesome creature called the Snakehead fish, which is able to breath air, allowing it to travel on land to find prey or migrate. Also known by the perhaps more fitting moniker "Fishzilla," the invasive fish has been discovered in parts of Oceania, and it may be only a matter of time until it makes its way to the Australian mainland.

According to a report in The Cairns Post, Snakehead fish have already been discovered on the southern coast of the neighboring island to the north, Papua New Guinea. The fish can grow up to three feet in length and are known to eat water birds, snakes and rodents. Snakehead fish are able to venture out of the water in search of prey which it devours whole.