Here are the Journey Book Secrets for Deep Blue!
is the Hatchetfish:
Below the bridge-ish part below the entrance to Crystal Reef.
Now the Oarfish:
This one is also pretty obvious; right above the secret entrance with the light.
This is the Gulper Eel:
Yes, I faked this picture, but this is where the Gulper Eel is located.
This is the Viperfish:
It comes to the left of the weird plants; I only got its backside.
Next, the Fangtooth:
It comes to the left of the lava pit.
Next, the Giant Squid (I faked this one too, but it's where it goes):
Here is the Coelacanth:
It comes in the upper left hand corner of Deep Blue.
And the Anglerfish (I love this one):
It comes beneath where the Hatchetfish comes by.
This fish is right next to the entrance to Crystal Reef.
And lastly, the Giant Isopod:
This one is a little bit camouflaged too. It comes out next to the giant standing up rock in the center part of Deep Blue.