If required to take a photo or share something tap the icon get off, then tap it again and repeat until your requirements are completed.

Fish	How to unlock
Blue Clownfish	Take a photo of a clownfish 3 times.
Clown tang	Take a photo of a tang five times.
Convict tang	Do nothing for 1 hour.
Cross damsel	Take a photo of a damsel five times.
Jewel Damsel	Tap the top left corner 1000 times.
Juvenile Spotted Boxfish	Start Application upon Notification.
Narwhale	Tap the top left corner 5000 times.
Nautilus	Use Delicious Food skill 50 Times.
Randals Goby	Take a picture of a Goby 3 times.
Snowflake Clownfish	Tap the Twitter button five times in settings.
Spotted Mandarin Dragonet	Start Application upon Notification.
Springer Dottyback	Share a photo three times.