Season 2 Episode 20 - Go Fish
The victorious Sunnydale High swim team throws a victory party at the beach despite the somewhat chilly weather, but Buffy isn't in the party spirit. She's gazing sadly out at the water when swimmer Cameron Walker sits down next to her, telling her he just wants to hang out with her, with no pressure. She stops Dodd McAlvy, another member of the swim team, from bullying the hapless Jonathan. Dodd stalks off to the water and disappears. A moment later, there is a scream and shredding sounds, and then something man-sized and monstrous stalks into the sewers, away from the steaming remains of what used to be Dodd.
Principal Snyder visits Willow in the computer class she's been teaching, and much to her delight offers her the position for the rest of the school year. But then he mentions the failing grade she gave swimmer Gage Petronzi, and not-so-subtly suggests that she change the grade... or else. Meanwhile, Buffy rides with Cameron in his Mustang, and his ceaseless chatter about the ocean segues into the beginnings of a sexual assault. Buffy breaks his nose defending herself, but in the nurse's office Cameron, Principal Snyder, and Coach Marin blame the incident on her, citing her revealing clothing. She tries to get some sympathy from Giles, Xander and Willow, but they're engrossed in a new problem — that of Dodd's eviscerated remains, found on the beach that morning. Cameron sits in the steam room as Coach Marin ordered, and then runs into Xander on his way to the cafeteria for a bite to eat. Xander hears a scream from the caf, and runs in to see the sickening sight of Cameron's remains, then turns to face a hideous fish-man creature!
Xander runs away, as does the creature, and he describes his encounter to Giles and the girls. Buffy, meanwhile, has found that Dodd and Cameron were the best and second best swimmers on the team, and suspects that Gage, the third best swimmer, could be next. She undertakes to keep an eye on Gage, but the swimmer notices and calls her on it that night at the Bronze. Her explanations fall on deaf ears, and Gage walks away from the Bronze, only to be attacked by Angel. Buffy hears his screams and runs to save him, but sees Angel spitting out the blood he'd tasted before running away. Something in Gage's blood didn't agree with Angel, and Buffy thinks it could be steroids. Then the girls get a shock — Xander has gone undercover (if a skimpy pair of Speedos can be called "undercover"), joining the swim team to keep an eye on Gage. However, he leaves Gage alone for a moment to pass Gage-watching duties to Buffy, and she hears a scream from the locker room. She runs in to see Gage being menaced by a fish-man, but even after she pushes Gage away, the swimmer continues screaming. Horrified, she watches as he tears off his skin to reveal another fish-man underneath.
Coach Marin runs in and helps Buffy escape the two fish-men, and later claims ignorance of the swimmers' steroid abuse. But when Willow finds evidence that the boys were definitely drugged, the girls' suspicion falls on Nurse Greenleigh. Xander finds out that the steroids are in the steam-room steam while Buffy and Giles go hunting for fish-men with a tranquilizer gun. Meanwhile, Nurse Greenleigh implores Coach Marin to stop exposing the boys to the drugs, but Coach says they "just need to adjust the mix," and calls her a quitter. When she continues to protest, he throws her down into the sewer through a hole in the floor, to feed "his boys."
Xander is wigged about being exposed to the steam, and Buffy goes off to question Coach Marin about its composition. She gets Coach to admit that he'd been trying to perfect some failed experiments the Soviets had tried on their Olympic swimmers using fish DNA. Then he pulls a gun on her and forces her into the sewer. She sees Nurse Greenleigh's half-eaten body float by, but Coach reassures her she won't be eaten. His boys have "other needs." As Giles rounds up the rest of the swim team, Xander heads off to see what happened to Buffy. He subdues Coach and pulls Buffy up out of the sewer, but as Coach attacks them from behind, Buffy trips him into the sewer, where "his boys" descend upon him in a brutal display of poetic justice. Xander and the rest of the swim team undergo plasma transfusions to reverse the effects of the steam, and the fish-men head for the ocean... returning home.