This method assumes that you have level 50 cooking. Also, this method burns no food in the process:
Level 50-59: 2,932 trouts - 11,728 profit
Level 59-69: 7,450 salmons - 59,600 profit
Level 69-74: 5,353 tunas - 16,059 profit
Level 74-86: 27,795 lobsters - 500,310 loss
Level 86-99: 94,367...