Observant Jewish families are very careful about mixing fish and meat even though it is a health issue (recorded in the Talmud), not a Kashrus issue. Fish and meat may be eaten at the same meal if they are properly separated. We do not know if the health issues are still relevant, or if the type of fish about which we are concerned is consumed in the USA. Some people even have a minhag to cook fish and meat in separated pots. Keystone-K requires separate pots at our establishments for the sake of those community members who follow this minhag.
It is for this reason that certain salad dressings carry a Fish designation (such as OU Fish), as someone might unwittingly use the dressing or sauce directly with meat. There is a Torah concept called “chamira sakanta yoser mei’issura” (danger to health is to be taken even more seriously than halocha prohibitions). Even though we are uncertain if the health issue with fish and meat is applicable in our circumstances we take it very seriously. It is for this reason that Keystone-K promulgates government health warnings that come to our attention. The following link will give you important information regarding a recall of ice-cream bars due to listeria contamination. These products are sold in our area. No Cholov Yisroel brands are currently included in the alert.