Based on the popular books by Marcus Pfister, the animated series follows the adventures of a boy fish with glittering scales and his friends in the underwater Bay of Neptune.
Episode 1
Sea Filly the Sea-horse, comes to the school of fish, and Rainbow and his best friend Blue, welcome her in.
Episode 2
Rainbow is excited to meet his hero, renowned hockey star Wayne Grunion when he comes to town for a visit.
Episode 3
In the school band, Mrs Chips gives Rainbow Fish the conch shell, the hardest instrument in the band to play. Rainbow is then forced to practice, and he does so, gradually making for a better performance at the school concert.
Episode 4
When Rainbow Fish and his friends attempt a dangerous sport called "Riptiding", Blue is swept away on a riptide, and Sea Filly and Rainbow must find him before it's too late.
Episode 5
Rainbow Fish gets a bad report card (he gets a "C"). But when he accidentally spills ice cream (from a kelp gusher milkshake) on it at Wanda's, his parents mistake the "C" grade for an "A". Rainbow must prevent them from meeting Principal Gefilte and learning the truth. For getting a "C", changing his grades, and lying that he got an "A", he is cave grounded by his parents until he gets his grades up. This means until he gets his grades up, he is "cave grounded" except for school (meaning he can only leave the house to go to school while cave grounded).
Episode 6
Rainbow is not enthusiastic about spending time with his grandpa while his parents are away at the store, thinking that he will be bored, but when his grandpa tells him an amazing story that hides an incredible secret, Rainbow discovers that old people can be exciting after all.
Episode 7
Rainbow fears visiting the dentist, but when he goes, he discovers that dentists are not as bad as he thought they were.
Episode 8
Rainbow mistakenly brags to his friends that he knows the famous pop star, Bruce Sturgeon, which lands him in trouble and causes him to force Bruce Sturgeon himself to perform at the school.
Episode 9
A new student, Sherman Shrimp, comes to school and Rainbow Fish treats him badly. However, after Sherman saves Rainbow from a sudden shipwreck, Rainbow realizes that he has been bad to Sherman all along.
Episode 10
Chomper, the school bully, gets lost in a canyon along with Rainbow Fish, and the two opposites must work together to find their way out.
Episode 11
Rainbow fools around with his father's golf club and breaks it, causing him to search for a new one before his father's big game with Sir Sword.
Episode 12
Ruby decides to babysit their guppy neighbors' baby, Ferdie, and says Rainbow is too irresponsible to help her. However, Ferdie turns out to be more troublesome than expected and swims away. Rainbow then finds him and Ruby apologizes for what she said.
Episode 13
Sir Sword needs to finish third grade, so he attends Rainbow's school, the School Of Fish.
Episode 14
Blue has a crush on Goldie, but he's too shy to ask her on a date, so Rainbow tells him what to say via a communicator made by Sea Filly. However, Chomper and Stingo soon ruin the plan.
Episode 15
When Blue becomes a hall monitor for the School Of Fish, he lets the power go to his head.
Episode 16
Blue gets a new baby sister, and he feels left out, all because of the attention his mum and friends are giving to the baby.
Episode 17
Rainbow lines a sea-monkey bowl with his sister Ruby's magazine, ruining the magazine itself in the process.
Episode 18
Rainbow learns a lesson about charity and works on a project involving just it.
Episode 19
Ruby starts spending time with Rainbow, Blue and Sea Filly the sea-horse, leading Rainbow to believe that she is trying to steal his friends.
Episode 20
Rainbow gets a job at the Candy Counter to earn money.
Episode 21
Rainbow takes up making movies, thanks to a new waterproof camera, and casts himself as Director.
Episode 22
Rainbow's pen pal is coming to visit him, and Rainbow is excited about it.
Episode 23
Sea Filly becomes the editor of the School Of Fish newspaper. Unfortunately, in her enthusiasm for journalism however, she soon becomes nothing but a tabloid gossip columnist and no fish is safe from her probing and humiliating articles. Rainbow comes up with a plan that ends with Sea Filly writing a false article about Principal Gefilte and losing her job. Sea Filly soon learns that real journalists have a responsibility to print only what they know is true.
Episode 24
In spite of some ongoing construction taking place outside the School Of Fish causing a big deal of noise, Rainbow is sent home early and gets freedom. A pair of burglars soon break into the Fish cave, and try to ruin it any way they can, all while Rainbow watches his favourite cartoon, "Silly Salmon" on TV by himself. Thanks to a 911 call being traced, Rainbow arrests the burglars and saves the day, pleasing Aqua and Sol in the process.
Episode 25
Rainbow and Blue start hanging out with a new clique called the High Tides, due to the chagrin of Sea Filly.
Episode 26
Sir Sword lends Rainbow a book that he becomes hooked on and cannot stop reading.
Episode 27
When Ruby encounters a series of unfortunate events one day, she believes that she has been cursed.
Episode 28
Rainbow's class has Dads' Day at school and all students' fathers are invited to describe their own, personal jobs. Rainbow is worried, however, as he thinks his father has a boring job.
Episode 29
Rainbow finds a hole in the ground that an extinct coelacanth called Carl swims out of. However, Carl spends most of his time in the modern world, trying to impress Ruby. This might be a reference to another Marcus Pfister book, called Dazzle the Dinosaur.
Episode 30
Rainbow and Blue compete for the role of class president. They both try to impress Sea Filly in order to get her vote.
Episode 31
Blue wins the clamball championship for his school, but only because no one sees him drop the ball anywhere.
Episode 32
Rainbow is suspicious of his sister, Ruby, when she starts acting very strangely. However, it turns out, that she is just making a surprise gift for their parents.
Episode 33
Rainbow's mother, Aqua, invites his teacher, Mrs Chips, to dinner, and Rainbow Fish is worried that Mrs Chips herself will act just like a teacher.
Episode 34
One difficult day, a glowing guardian angel fish shows Rainbow Fish the value of his life.
Episode 35
Rainbow Fish fears that both his parents, Sol and Aqua, are planning to sell the cave to two fish called Ret and Snapper, and so his friends attempt to make his house as much of a wreck as possible to avoid it being sold. However, Rainbow then discovers his parents were planning to build a new recreation room.
Episode 36
Rainbow and Ruby prepare an anniversary dinner for their parents.
Episode 37
Rainbow saves a whale's life, and, in return, the whale (Leslie David Baker) becomes his bodyguard.
Episode 38
Rainbow is not pleased when his mother, Aqua, gets a job in his school.
Episode 39
After being teased by her classmates for not being feminine enough, Sea Filly decides to take up cheerleading, causing Blue and Rainbow to worry about her becoming a different person altogether.
Episode 40
Rainbow is embarrassed after failing to stand up to Rocko Rockfish (Alan Marriott), a bullying second grader.
Episode 41
After watching Rainbow and Blue play it in Shipwreck Park, Sea Filly becomes addicted to a 2000 computer game called "Clam Blaster" and hardly does anything else. However, when she brings the video game to the School Of Fish one day and plays it there during a difficult maths test with Mrs Chips, she soon discovers that the video game itself is "dumb, violent and intellectually worthless".
Episode 42
Rainbow, Blue, and Sea Filly hear the tale of two feuding crabs who were once song-and-dance partners, and then, they all set out to bring them back together, once and for all.
Episode 43
Sea Filly gets a bad grade on a maths test at the School Of Fish and worries greatly.
Episode 44
When Blue looks at his book and mistakenly thinks that his ancestors were royalty, he starts acting like a prince.
Episode 45
When Chomper's cousin Slick (Macaulay Culkin), a pool-playing master, comes to Wanda's refreshment shop, he beats everyone in Pool by secretly cheating. Rainbow, unaware of this at first, is in awe, and decides to become his assistant, then discovers his secret. Rainbow then declares a match to determine that Chomper's relative is cheating. Rainbow then wins, and the other player leaves the shop forever.
Episode 46
Rainbow tries to put Sea Filly in the Halloween spirit, but then has a haunting Halloween dream, and wakes up to find that Sea Filly has actually scared him in his sleep.
Episode 47
Phineas T. Gronch is planning to permanently demolish the Mollusk Reef Villas as well as wipe out half of Neptune Bay to build a shopping mall in its place. Rainbow, Blue and Sea Filly have to stop him in time, or they'll all be for it.
Episode 48
Rainbow and his family go on a camping trip.
Episode 49
Important friendship is tested when Blue comes to stay in Rainbow's cave.
Episode 50
Chomper is given the lead role in the school play, but he mistakenly believes that voice acting is for wimps.
Episode 51
Rainbow's love of kelp gusher drinks causes him to get a nasty case of hiccups. It's Wanda the Octopus who eventually finds the "wild" cure.
Episode 52
Rainbow Fish helps Sir Sword dressed up as Santa Sword on Christmas Eve.
