an edit that i did of a korean wiki translation (by google translate). Some of the names translated weird so..
i tried my best to edit it so it made sense. SOME OF THESE MAY BE INCORRECT!
Blue Clownfish: unlock after taking picture of a clownfish 3 times
Black & White Clownfish: Beginners Pack purchase unlockable
Snowflake Clownfish: unlock after pressing Twitter button in settings five times
Randall's Gobi: take a picture of a gobi 3 times to unlock
Spotted Mandarin dragonet: 10% chance opportunity to get the hidden fish (10 minutes after notification), when you exit the app, there is a probability that after 30 minutes the game will send you a notification with a phrase telling you to play the game and unlock the hidden fish. if you play within 10 minutes of the game sending you the notification you will have a chance of unlocking.
Crown Tang: unlocks after taking 5 pictures of a tang
Victrex Kern Teng: Unlocks when you do not perform any action for 1 hour
Cross damsel: unlockable after 3 pictures of a damsel taken
Jewel damsel: unlocks when you have tapped the upper left corner 1000 times
French Angelfish: unlocks after taking and storing 3 pictures of an angel.
Stylish Moorish Idol: Unlock after taking picture of treasure chest five times. classifies as Angelfish.
Scribble Angelfish: click on More photos in instagram photo contest 10 times
Springer Dottie back: share your photos via Social networking service times
Pajama Cardinal: play 20 times during a 24 hour time period to unlock. classifies as Butterflyfish.
Mahi Mahi: play 10 times at midnight. Parrot fish type.
Ryan Fish: Intermediate Pack Purchase
Camel blowfish: take and share picture of blowfish three times to unlock.
Spot Painted Blowfish: 10% chance opportunity to get the hidden fish (10 minutes after notification), when you exit the app, there is a probability that after 30 minutes the game will send you a notification with a phrase telling you to play the game and unlock the hidden fish. if you play within 10 minutes of the game sending you the notification you will have a chance of unlocking.
Bellied seahorse: take and share picture of seahorse 3 times to unlock.
Pygmy Seahorse: unlock after playing at dawn at 4:00 (AM) 5 times. turn on at four o'clock PM to obtain access to 4 AM. (Bug? this was on the wiki, but it's probably been patched now. feel free to try it out!)
Luminous deep-sea jellyfish: unlocked when you take 10 photos of jellyfish.
King Jellyfish: advanced purchase unlockable pack (advanced pack purchase?)
Leatherback turtle: open mystery chest 50 times
striped Marlin: Take picture of the striped marlins when they visit you. 10% chance of seeing them every 30 minutes if you have app open.
Commerson's Dolphin: take and store 3 pictures of dolphins to unlock
Narwhal: Unlocks when top left corner of the screen is tapped 5000 times. classifies as Dolphin.
Manta ray: unlock after sharing 3 pictures of sting ray
Hammer Shark: unlocks after saving 3 pictures of sharks
Whale Shark: 10% chance opportunity to get the hidden fish (10 minutes after notification), when you exit the app, there is a probability that after 30 minutes the game will send you a notification with a phrase telling you to play the game and unlock the hidden fish. if you play within 10 minutes of the game sending you the notification you will have a chance of unlocking.
Humpback whales: unlockable with Master Pack purchase
Harp Seals: Supreme Unlock Pack purchase. Estimated to be similar to the dugong