Marlins prospect Eiver Mosquera gets 80-game suspension for doping positive

Miami Marlins right-hander Eiver Mosquera was suspended for 80 games after testing positive for Boldenone under Major League Baseball’s minor league drug program. The penalty was immediate and without pay, and MLB said Mosquera was on the roster of the Single-A Jupiter Hammerheads when the suspension was announced.

Mosquera is 19 and has been working through the Marlins’ development system, with his 2026 line showing 3-3, a 4.50 ERA, nine starts and three relief appearances for the rookie-level Florida Complex League Marlins and Class A Jupiter. MiLB and Baseball-Reference list his full name as Eiver Antonio Mosquera. He was born Sept. 10, 2006, in Caja Seca, Venezuela, stands 6-foot-2 and weighs 175 pounds, and throws right-handed. For a young pitcher still being evaluated as both a starter and reliever, an 80-game suspension cuts directly into innings, coaching reps and the time needed to turn a prospect into a major league option.

Boldenone is treated as a performance-enhancing substance in MLB’s 2022 joint minor league drug program, which covers players on both 40-man and non-40-man rosters. MLB’s Player Resource Center says the drug prevention and treatment programs were created to prevent and end the use of prohibited substances that can be hazardous or give players an unfair competitive advantage. The league also said Mosquera was the ninth player disciplined this year for a drug violation.

Minor league testing has been part of baseball’s enforcement system since 2001, and Boldenone cases have kept surfacing across the lower levels. Miami minor leaguer Deivis Mosquera was suspended in November 2022, and Houston Astros minor league catcher Emilio Gonzalez received a 56-game suspension in August 2025 after testing positive for Boldenone in a program for players assigned outside the United States and Canada. In March 2018, Twins infielder Jorge Polanco was suspended for 80 games after a positive test for Stanozolol, a reminder that the standard first-time penalty can halt a career at any level.

For the Marlins, the suspension removes one of their young arms from competition and puts the focus back on player education and oversight in the minors, where many international prospects arrive with limited visibility and a short runway to the majors. For Mosquera, the consequence is immediate: 80 games lost, no pay, and a longer road back in an organization that will now have to judge whether his future survives a drug case before he has even reached the big leagues.