I used tuna packed in olive oil, so I drained the olive oil from the can into the skillet and added 2 tablespoons of butter before sautéing carrots and onions. One can use other thickeners like arrowroot, cornstarch, tapioca, potato flakes, or just “cook down” longer over low heat until sauce is reduced/chowder is thickened. Finally, like any other soup I make, I’m always game to add in little bits of “this and that” from the refrigerator. This time it was one cup of brown rice. Potatoes and rice together might seem like too much, but the combination worked just fine and the instant thickness put this chowder on the table faster than usual.