Toronto Blue Jays Minor leagues Fishman was selected in the 30th round of the
2016 Major League Baseball draft by the
Toronto Blue Jays. He said: "It was the best feeling in the world." In being selected, he became the first Union College player to be taken in an MLB draft. He signed with the Blue Jays on June 17, for a
signing bonus of $50,000 and payment of his senior year tuition, approximately $65,000. Fishman was assigned to the Rookie-level
Gulf Coast League Blue Jays. In 2016 in seven appearances, including one start, he posted a 0–1 record, 4.80 ERA, and 13 strikeouts in 15 innings pitched. In 2017, Fishman pitched one scoreless inning for the Gulf Coast League Blue Jays, pitched in 14 relief appearances for the
Vancouver Canadians of the Low–A
Northwest League for whom he was 1-0 with 1 save and a 1.17 ERA and 4 walks and 23 strikeouts in 23 innings, and pitched four times in relief for the
Lansing Lugnuts of the Single–A
Midwest League, for whom he was 0-1 with a 4.05 ERA and zero walks and 15 strikeouts in innings. He pitched in one game for the
Buffalo Bisons of the Triple–A
International League, pitching perfect innings with one strikeout. Lefties batted .197/.250/.250 against him, in 76 at bats. In 2019, Fishman pitched for the
New Hampshire Fisher Cats of the Double–A
Eastern League. He held lefties to a .223/.281/.258 slash line and a .540 OPS, and his fastball was top-10 in horizontal movement among upper-level lefties. Fishman did not play in a game in 2020 due to the cancellation of the minor league season because of the
COVID-19 pandemic.
Miami Marlins On December 10, 2020, Fishman was selected by the
Miami Marlins in the first round, with the 12th pick, of the minor league phase of the
Rule 5 draft. Pitching for the
Triple-A East Jacksonville Jumbo Shrimp in the 2021 season, he was 5-1 with one save and a 3.67 ERA, pitching innings over 34 games (2 starts). At the time, in Triple-A Fishman had a 1.87 ERA with 43 strikeouts and 16 walks in innings. He had an 0.992 WHIP (10th-best in the International League), 5.6 hits per 9 innings (7th), a 54.3% ground-ball rate, 24.4% strikeout rate, and 9.1% walk rate, had held lefties to a batting slash line of .163/.240/.233 in 86 at bats, and had pitched at least two innings in 14 of his 25 relief appearances. Fishman made his MLB debut with the Marlins that same day. In 11 innings with the Marlins over seven games, he recorded a 4.09 ERA and a WHIP of 1.18. He threw a
sinker 60% of the time (with an average drop of 38 inches; the MLB average was 23 inches), and a
slider 40% of the time (with an average drop of 48 inches; the MLB average was 37 inches). Fishman was designated for assignment by Miami on August 1 after
Jesús Luzardo was activated off of the injured list. He cleared waivers and was sent outright to Triple-A on August 4. After six appearances in Triple–A, in which he logged a 2.79 ERA in innings, Fishman was selected back to the major league roster on August 27. He tossed a scoreless inning against the
Tampa Bay Rays before he was designated for assignment again on August 31, when
Trevor Rogers was activated from the injured list. He was again sent outright to Triple–A Jacksonville on September 3. In his minor league career through 2022, he was 13-8 with 15 saves and a 2.97 ERA in 279 innings in which he struck out 288 batters, with a WHIP of 1.12. He was assigned to the Triple–A
Las Vegas Aviators to begin the 2023 season, but surrendered 8 runs on 9 hits and 1 walk with 4 strikeouts in 3.0 innings of work. After beginning a rehab stint with the rookie–level
Arizona Complex League Athletics, in which he was 0-1 with a 2.25 ERA and struck out 7 batters in 4 innings, Fishman was released by Oakland on July 1, 2023.
Long Island Ducks On July 25, 2023, Fishman signed with the
Long Island Ducks of the
Atlantic League of Professional Baseball. In 2023 with the team, he was 2–0 with a 4.82 ERA, as he gave up 12 hits and four walks and struck out 19 batters in innings. In 14 appearances for the club, he posted a 2-0 record and 2.25 ERA with 20 strikeouts over 12 innings of work. Fishman became a free agent following the season.
Toros de Tijuana On April 19, 2025, Fishman signed with the
Toros de Tijuana of the
Mexican League. ==Team Israel==