ה צִיר דָּגִים טְמֵאִים, אֵינוֹ אֶלָּא מִדְּרַבָּנָן. לְפִיכָךְ מֻתָּר לִקְנוֹת מֵהָעוֹבֵד כּוֹכָבִים דָּגִים מְלוּחִים, טְהוֹרִים, אַף עַל פִּי שֶׁמֻּנָּחִים עִם הַטְּמֵאִים בִּכְלִי אֶחָד, שֶׁמָּא לֹא נִמְלְחוּ יַחַד. הַגָּה: וְיֵשׁ אוֹסְרִים, אִם מֻנָּחִין עִם הַטְּמֵאִים בְּחָבִית אַחַת. וְכֵן נוֹהֲגִין שֶׁלֹּא לִקְנוֹתָן, אֲפִלּוּ אִם רוֹאִים רַק שֶׁמֻּנָּחִים עִם הַטְּמֵאִים הַמְּלוּחִים בְּעִרְבּוּב עַל הַשֻּׁלְחָן שֶׁמּוֹכְרִין אוֹתָן שָׁם (ת"ה סי' קע"ד וְהַגָּהוֹת ש"ד וְש"ד סִימָן כ' וְאוֹר זָרוּעַ וְאָרֹךְ כְּלָל י"ג ומָרְדְּכַי בְּשֵׁם תּוֹסָפוֹת הר"ר יִשְׂרָאֵל), מִלְּבַד בְּהֶערִינְ"ג וּמרקרי"ש דְּמַתִּירִין בְּכָל עִנְיָן, דְּוַדַּאי אֵין נִמְלָחִים עִם הַטְּמֵאִים, מִשּׁוּם דְּאֵין דֶּרֶךְ לְמָלְחָן עִמָּהֶם (מָרְדְּכַי). וַאֲפִלּוּ בִּשְׁאָר דָּגִים, אֵין לְהַחֲמִיר לְפַשְׁפֵּשׁ וְלִבְדֹּק אִם יֵשׁ בֵּינֵיהֶם דָּגִים טְמֵאִים. וְאִם רוֹאֶה שֶׁהַדָּגִים הַטְּמֵאִים שְׁרוּיִים בְּמַיִם עִם הַטְּהוֹרִים, אֲפִלּוּ בְּהֶערִינְ"ג יֵשׁ לְאָסְרוֹ (הַגָּהוֹת ש"ד בְּשֵׁם מהרא"י וְר' יְרוּחָם). אֲבָל אֵין חוֹשְׁשִׁין שֶׁמָּא נִשְׁרוּ, כָּל זְמַן שֶׁאֵין רוֹאִים (שָׁם). וְכָל זֶה לְכַתְּחִלָּה, אֲבָל בְּדִיעֲבַד, שֶׁכְּבָר קְנָאָן, יֵשׁ לְהַתִּיר בְּכָל עִנְיָן, מִשּׁוּם דְּצִיר דָּגִים דְּרַבָּנָן, וְאָמְרִינָן שֶׁמָּא בִּתְחִלָּה לֹא נִמְלְחוּ יַחַד, וְאֵין חוֹשְׁשִׁין אַחַר כָּךְ לִבְלִיעָתָן זֶה מִזֶּה (אָרֹךְ). וְדַוְקָא דְּלֵי בְּהוּ שַׁמְנוּנִית, וּסְתָם דָּגִים מְלוּחִים לֵית בְּהוּ שַׁמְנוּנִית, אֲבָל אִם אִית בְּהוּ שַׁמְנוּנִית, אָסוּר מִדְּאוֹרָיְתָא, וּסְפֵיקָא לְחֻמְרָא (שָׁם). וְהֵיכָא דְּהַדָּגִים מְלוּחִים יְבֵשִׁים, מֻתָּר בְּכָל עִנְיָן, מֵאַחַר דְּהַטְּמֵאִים גַּם כֵּן יְבֵשִׁים (מהרא"י בת"ה). וְנָהֲגוּ לְהַחְמִיר גַּם בָּזֶה לְכַתְּחִלָּה, אִם מֻנָּחִים בֵּינֵיהֶם (שָׁם).
5 Non-kosher fish brine, is only rabbinic. Therefore, it is permitted to purchase salted fish from a non-Jew, [that are] kosher, even though they were placed with non-kosher [fish] in the same vessel, lest they were not salted together. Rema: There are those who prohibit, if they were placed with non-kosher [fish] in one barrel. We are accustomed to not purchase them, even if we see that it was only placed with [other] non-kosher salted fish in a mixture on the table that they are being sold on. (Trumat HaDeshen 174 and Hagahot Sh''D, Sh''D Siman 20, and Or Zarua and Arukh Klal 13 and Mordechai in the name of the Tosafot Rabbi Israel), except for herring and markrish which are permitted in every circumstance, and definitely when they are not salted with non-kosher [fish], because it is not the way to salt them with them [the other types of fish] (Mordechai). Even regarding the rest of the fish, one should not be stringent to rummage and check if there are non-kosher fish among them. If one sees that non-kosher fish are being soaked in the water with kosher [fish], even herring there [is what to say] to prohibit it (Hagahot Sh''D in the name of MaHaRA''I and Rabbi Yerucham). But there is no concern lest it is being soaked, the whole time that we don't see [them] (ibid.). All of this is from the outset, but after the fact, when has already purchased them, there is [what to say] to permit them in every circumstance, because fish brine is rabbinic, and we say lest they were not salted together in the beginning, and we are not concerned after that of it absorbing from one to the other (Arukh). And specifically when suspended in oil, and just salted fish do not have oil, but if there is oil, it is prohibited by the Torah, and doubt [regarding Torah law we lean towards] stringent (ibid.). And in the case that the fish are salted dry, it is permitted in every circumstance, after the non-kosher [fish] also are dry (MaHaRA''I BT''H). And we are accustomed to be stringent also with this from the outset, if they are placed among them (ibid.).