Sources also told MLB.com that the Reds' 2018 first-round draft pick Jonathan India is among the names being discussed in a potential swap. The Los Angeles Dodgers and San Diego Padres are also in talks with the Marlins regarding the catcher and are seeking the best package of two to four prospects in the swap.
The Marlins have also shown interest in Reds star prospects Nick Senzel, Taylor Trammell and Hunter Greene, in addition to India.
The Atlanta Braves have also been linked to the Marlins catcher.
Senzel is the No. 6 prospect in baseball, according to MLB Pipeline. Trammell is the No. 16 overall prospect, while Greene lands at No. 31. India -- the No. 3 overall pick in the 2018 MLB June Amateur Draft is ranked as the No. 53 prospect.
Realmuto, 27, hit .277 with 21 home runs and 74 RBIs in 125 games last season for the Marlins, earning his first All-Star selection.
The five-year veteran owns a career .279 batting average with 59 long balls in 540 games for the Marlins.
Realmuto is set to make $5.9 million this season and is eligible for arbitration in 2020.