If one cooked meat and fish in the same vessel [and there was not 60x] does the vessel need to be Kashered?
Some Poskim rule that the pot must be Kashered through Hagalah. Other Poskim however rule that the vessel is not required to be Kashered and must rather simply wait 24 hours prior to use. Practically one may use the vessel after 24 hours have passed since the forbidden use.
 See Darkei Teshuvah 116/28; Kaf Hachaim 116/13
 Tiferes Lemoshe in name of his grandfather Yaakov, brought in Pischeiy Teshuvah 116/3; Birkeiy Yosef 116 in Shiyurei Bracha 7; Shemiras Hanefesh 12
 The reason: As the taste absorbed in the pot is forbidden to be eaten [due to Sakana] just as is any other non-Kosher food, and it hence needs to be Kashered.
 Divrei Malkiel 2/53; Kaf Hachayim 116/13
 The reason: As the taste of meat and fish does not prohibit meat and fish due to Sakana, as expaliend in Issur Viheter 23/7 and Taz 116/2, hence the allowance to cook fish in a Ben Yomo meat pot. [Kaf Hachaim ibid; Divrei Malkiel ibid]
 Kaf Hachaim ibid