When you take pictures with your Splash-Cam of specific species, a window might pop up saying “Behavior Snapped”. You have just fulfilled a Splash-Cam mission! Tap the green tick and the go to the Aquapedia page for this species and collect a small reward for taking the picture and once you have collected the reward the information will now be displayed.
Check the Aquapedia to see what species information you are missing and which rewards you can claim.