Bloodline removal is the only hard part.

Yes, but you only need to worry about the bloodline.

Start with a sharp, long knife (boning or filleting knife works) and keep the fish on ice the whole time. Scale it if needed, gut it if not already done, then fillet: cut behind the gills and run the knife along the backbone to remove each side. For steaks, you want cross-sections, so leave the fillet whole and slice perpendicular to the spine into 1-inch thick steaks.

The dark red bloodline running through the center is what makes tuna taste fishy or metallic. Trim it out with a smaller knife. You don’t have to be surgical — just get the darkest red part. The rest of the meat is clean,