I have no medical data on this but I do notice with my cats two get gassy if they eat whole raw fish. A couple of times a month I will buy them a whole fresh fish or frozen whole fish like smelt and dethaw it. I noticed two of my cats will have gas and loose stools for about a day after. One is so smelly even my other cats will avoid him. An alternative explanation would be these cats have a specific intolerance to an ingredient in the food or fish. This might be a good question for Dr. Lisa if she is around today.