Jumbo has a waist bag and two front teeth. He also seems to be friends with Oscar and plays strategy games with him. Jumbo seems shy but friendly. Like Albert, Jumbo gets bullied by Jocktopus often. While Albert is a reading nerd, Jumbo is a math and science geek.
His first major role is in the episode "Big Fish". Jumbo called Milo when they were eating lunch. After Jumbo finished his pudding, he leads Milo to a rusty, old city, and thinks he might be able to help him. He asks Milo if he knows Jumbo as a man of science, but Milo says he just thought he was a weirdo. Jumbo tells him that means he knows he doesn't exaggerate, and tells him to believe what he's about to say and show to him. Jumbo then shows him the big tank and explains to Milo that he used to be tiny and was named "Shrimp Shrimp", so he went to the big tank, sat down on the chair, and grew big and strong. But he warned Milo to only sit there for 5.03 minutes, or there will be big consequences. After Milo didn't listen and turned extremely huge, Jumbo was angry and told him he warned him about the consequences. He says there is only one thing to make Milo small again: the shrink tank. Jumbo then listened and danced to Oscar and Bea's "Inspirational Song".
Jumbo helped the boys create their float for the Homecoming float competition. He at first helped build the machine, and then, along with the other boys, battled the girls at the football field ("Fish Floaters"). When Milo sucked out all of the water in the tank, the whole class had to evacuate, with the exception of Jumbo, who stayed in the classroom to "analyze" the atmosphere ("Parasite Fright").
Jumbo fell for Milo's plan, along with all of the other students, when Milo told them about the "Cinco De Milo" party, which was only a scam to lure everyone outside the tanks. At the party, Jumbo stated that the ratio of chips to dips was all wrong ("Pamela Hamster Returns"). Like all of the other students, Jumbo preferred Randy's fridge hats rather than Milo's fridge hats ("Milo's Big Idea"). When watching the basketball game between Freshwater High and the geckos, Jumbo cheered for the Freshwater mascot. Albert questioned Jumbo Shrimp who was inside the mascot costume. Jumbo told him that nobody knows ("Mascotastrophe"). In Oscar and Bea's morning announcements, Jumbo was their manager. When Oscar quit his job as the morning announcer, the cafeteria was closed since Oscar didn't announce the news, so all of the students went hungry. When all of the students ran out of the school, Jumbo chewed on the rail in the side of the school ("Good Morning, Freshwater"). When Randy was about to read Bea's diary in front of the whole school, Jumbo went to the auditorium because he thought they were supposed to show a movie. Jumbo, along with the other students, threw tomatoes at Randy after finding out that he blackmailed Bea to go on a date with him ("Diary of a Lost Fish").
When Bea and Milo tried to help Oscar pick a club, they ended up walking to the map club, where there were only 2 people in the club: Jumbo Shrimp and Albert Glass. Bea told Oscar that he shouldn't join the map club, due to it being "nerdy". Later, it is shown that Bea actually signed up for map club. When Albert and Jumbo needed people to join their club, they asked to to sign a paper. Bea, thinking that they want her autograph, signed it. Bea tried several times to get out of map club, but so far didn't succeed doing so. Bea then told Albert and Jumbo that she has a map to find "missing maps", which causes Jumbo and Albert to try to look for it, making Bea go out and help Oscar in his cheer routine ("We've Got Fish Spirit"). Jumbo was just as excited going to Pupu Goodtimes amusement park as the other students. Jumbo told Oscar to join him and Albert try to beat a cup game to win a "Limited Edition Fork Saber". However, Jumbo's throws were all inaccurate, but very strong, and neither Jumbo, Oscar, or Albert knocked all the cups down. Albert suggested that they should ride the Pu-Panator so that Oscar could throw from there. They ended up knocking the cups and winning the Fork Saber ("Good Times at PuPu Goodtimes"). In the "Potatoes for Winter" play, Jumbo first played as a citizen of El Gratin. Each of the citizens honored the Great Potato, so when the Great Potato got stolen, Jumbo's character was saddened about the loss of their enchanted spud. Jumbo then played as a back-up singer for Milo's rap. Finally, Jumbo played as the prince's assistant. The prince (Randy) told his assistant to pick the filthiest citizen and ask her to pull Randy's cart ("Fish School Musical").
When Oscar told everyone to trick-or-treat outside the tank, Jumbo Shrimp and Albert joined their plan to get through Halloween without running into Jocktopus. Jumbo's costume was an owl ("Halloween Haul"). Jumbo and Albert tried to win the talent show together. When Clamantha and Shellsea had an argument in their dance group, Jumbo took Shellsea's side, only because he's scared of her. At the end, Jumbo and Albert watched Bea's dance group preform onstage ("Fish Talent Show"). Jumbo Shrimp auditioned for the Hokey Poke commercial, only to get rejected by Chief ("Bea's Commercial"). When Milo and Oscar tried to figure out why Steve Jackson is so perfect, Jumbo and Albert told them that's the question all boys are trying to answer. Jumbo put down a projector and showed Milo and Oscar that Steve Jackson's perfection lies within his hair. When Steve walked past the boys, he accidently dropped his hair gel, in which the boys take and they all swam to the back of the school. Each of the boys put the gel on their hair, and they all became popular in Freshwater. When Jumbo was about to eat his pudding, he threw his spoon and dumped the pudding in his mouth, which made Esmargot and Clamantha drool. When the boys put on more hair gel in the bathroom, Oscar pointed out that they will probably run out of hair gel by the next morning. So Oscar puts the hair gel in his locker. Later when Oscar's hair was turning back to his normal hair-style, he went back to his locker to get more hair gel without anyone noticing. However, when Oscar went to his locker, he saw Albert and Jumbo trying to open Oscar's locker to get more hair gel as well. They all fight for it, but when Albert pulls out a string of Jumbo's hair, Jumbo became extremely angry, so he pulls out Albert and Oscar's hair and put it on his hair. Steve Jackson finds the boys fighting over his hair gel, so he tells them that nobody is perfect, and that if you try your best, good things will happen. At the end, Steve and the boys go to get a meal at the Hokey Poke ("Hairanoid").
At the beginning of one morning, Jumbo Shrimp was setting posters all over the halls, panicking about his lost sandwhich. Later when Milo was falsely accused of gluing Mr. Baldwin into his chair, he ran to Jumbo, who was the head hall monitor. Milo started asking him if he can help him. Jumbo told Milo that they might be friends, but he knew that Milo was a fugitive and was told to put him to detention. Milo then showed Jumbo a piece of the glue, which was cut into a lightning bolt shape by Albert Glass. Jumbo tried exaiminating the glue piece, but he still couldn't tell who did it. Milo, deciding theres no other way, put on a fake beard to go into hiding, and then asked Jumbo if he has any glue to stick the beard on. Jumbo told Milo that he has it in his pouch, although he notices that he left it in the classroom. Milo then realized Jumbo Shrmip was the one who glued Mr. Baldwin to his chair, so Milo chased after Jumbo. Jumbo ran away to avoid detention, and ended up in Fish Niagara Falls. Jumbo was up on top of the waterfall, and with Milo about to go to detention, begging him to confess, Jumbo surrendered and told everyone what really happened. In the morning, Jumbo was setting up posters of his lost sandwhich, and was about to glue one of his posters in Baldwin's classroom. But he got distracted by how much glue was in his glue stick, and he dropped the glue in Baldwin's seat, causing Mr. Baldwin to sit on it afterwards. Mr. Baldwin heard the whole story, and when Jumbo told Baldwin he was accepting the fact that he's going to detention, Baldwin told Jumbo that he doesn't have to go, but he also tells Jumbo that he's the one who ate his sandwhich ("Milo on the Lam").
- He was first known as Shrimp Shrimp ("Big Fish").
- Koi could be in love with Jumbo because she was seen comforting him once.
- He is the third biggest fish in Freshwater High behind Jocktopus and Koi.
- He grew bigger by sitting in the "Big Tank" which he encouraged Milo to go into. ("Big Fish")