Rainbow Fish

Rainbow Fish: The proud, vibrant fish that lives with his mother and father. His favorite movie is Claminator 12. He loves it so much that it can lead to problems. He likes to play Clam ball, a fictional game which is in a place mostly.

Principal Gefilte: The proud Principal of The School of Fish, he is strict about behavior. Sometimes, he can get vain. Rainbow Fish gets annoyed when he insists that they all have to write book reports.

Sea Filly: In one of the episodes, she is a new girl in school. She is a beautiful seahorse, though she is half mermaid, half seahorse. She eventually becomes friends with Rainbow and Blue. She is often seen reading books

Blue: Rainbow Fish's best friend, who is more down-to-earth and thoughtful than Rainbow Fish. He also enjoys playing Clam ball, and also loves Claminator 12. He is a blue fish and has a baby sister called Turquoise. She is a turquoise fish.

Ruby: She is Rainbow Fish's older sister who is a teenager. She is arrogant, bossy, self-centered and ruby-colored. Constantly, she gets Rainbow Fish into trouble, because she gets jealous, although she actually loves him. She has her own personal nickname for Rainbow Fish; she calls him "Barnacle Boy". This is an allusion to SpongeBob SquarePants.

Mrs. Chips: The teacher of the school. She teaches history, mathematics, science, and literature.

Wanda the Octopus: She is the owner of the Neptune Bay fast food restaurant. She very wise and when Rainbow Fish is down she will always gives him advice.

Chomper and Stingo: The two bullies of the school. They do not really commit acts of physical violence but they can bully and tease Rainbow Fish and his friends. Chomper is a shark while Stingo is a stingray. Chomper bullies more often than Stingo. They often call Rainbow Fish "Rainbow Creep", but sometimes call him other names, like on one episode, "Rainbow Girl".

Sherman: The smallest of the school. He is a salt-water shrimp. To him everything looks big. In the episode where he arrives to Neptune Bay, Rainbow Fish treats Sherman as a shrimp. In the end when Rainbow Fish gets stuck deep in the bowels of a shipwreck, Sherman hears from the TV and goes and rescues Rainbow Fish. Rainbow apologizes for his behavior.

Sol and Aqua: Aqua is an aqua-colored fish and is Rainbow Fish's mother. Sol is purple and is Rainbow's dad. They help their daughter and son whatever way they can and will always provide them with great courage.

Sir Sword: Local swordfish, upper-class and a bit of a busybody. He is sometimes grumpy, sometimes civil, but always seems to think he is better than everyone else. Plays Santa Sword to the kids at the local Guppies hospital.

Ret and Snapper: The two builders. They appear in only one episode, Moving Away. Rainbow Fish thinks they are going to be moving and Ret and Snapper will buy the house. He and his friends plan to make the house as much of a wreck as possible in order to put off any potential buyers. His parents reveal they were going to build a new recreation room.

Goldie: She appears in only one episode, Shy Blue. She has a crush on Blue, and Rainbow Fish attempts to bring them together. However, Chomper and Stingo soon ruin the plan.

Rainbow Fish's other classmates: They do not speak in any episode, but, however, they are different shapes, sizes and color. The first one is: a brown fish, the second one: has long body and colored violet, the third one: colored gold and has a redish-like lips, the last one: has a sleek body and has the same color as the second one. Their names are not revealed in any episode since.