Borris is a male blue butterfly fish and the first character to play with. He grows the fastest of all characters.
Layla is a female yellow queen triggerfish and the 2nd character. Her levels give you the suck ability
Eddie is a female green anglerfish. She could emit light using the bulb-like object attached to her head, she's the 3rd character in game.
Peter is a African Pompano and the 4th character to play with. From the start of his levels, there are cuttlefishes.
Harry is a male blue and green humphead wrasse and the 5th character. His levels introduce Pelicans in the level Plunging Peril
Goliath is a male Great White Shark and the last and 6th character ingame. He's the biggest character ingame and the first to fight the intruder.
The Mystery fish, Alien Intruder or Intruder isn't playable until you have truly deafeted him. Then you can use the Intruder profile to play as him all levels again.