This is a full digital drawing of the Deep-sea dragon I drew earlier today. This type of dragon is inspired by the Angler Fish. I did take the libery of changing some things, like the finns on the arms and the addition of teeth.
Here is some species information on the dragon:

Habitat: Lives in the deep sea, close to the seafloor but sometimes comes up to higher levels of the sea where some sunlight can reach.

Diet: Carnivores and primarily eats smaller fish. They rarely go out and hunt larger fish and instead prefers to hide and hunt smaller fish that they can easily snack on.

Mating habits: The males and females rarely meet eachother, only during mating season do they come out and engage with one another. They attract mates by glowing different colors and creating bright lightshows to impress. After mating, the females will grow their eggs inside their bodies and wait untill the water becomes warmer. When the water is warm enough, usually during the summer, she will lay her eggs in big batches in caves or small dug-outs. Afterwards she leaves the eggs and ususally never returns.

Abillities: While hunting, they will usually turn off the glow their scales and finns provide. This is for camoflage so their prey can't spot the danger they are in. While attracting mates, they can glow a variety of different hues and colors. The most normal colors are blue, green, purple and pink.

Relationship to humans: Because of how difficult they are to locate, and their amazing camoflage in the deep sea, many have never been captured or tamed. They are also solidary animals so it's difficult to track them using others of their kind.