How do you get marlin if we already have red heart?

To catch a marlin after obtaining a red heart, you'll typically need to go to a specific fishing location known for marlin. Equip the right fishing gear, such as a strong rod and bait suitable for marlin. Timing can also be crucial, so ensure you're fishing during the right season or time of day. Be patient, as marlin can be elusive and require skill to reel in once hooked.