Here's a close-up view of the frozen turkey hearts and turkey livers that will go into our discus fish food. They are thawed before cooking to remove excess blood and water. Always cook the turkey livers thoroughly. Cooking the turkey hearts will help reduce the excess fat. Cooking the turkey hearts and livers also makes them much easier to grind.
You can substitute other muscle meats, like beef heart, instead of using turkey hearts. Beef hearts are probably easier to find than turkey hearts. If you can't find beef heart, just ask your local butcher to order some. Remember to remove all the excess fat when using beef heart. You can also use very lean ground beef instead of hearts in your discus fish food recipe.