Man Lā Yaḥḍuruh al-Faqīh
Hadith 9494162 - وَ رُوِيَ : "فِيمَنْ وَجَدَ سَمَكاً وَ لَمْ يَعْلَمْ أَنَّهُ مِمَّا يُؤْكَلُ أَوْ لاَ فَإِنَّهُ يُشَقُّ أَصْلُ ذَنَبِهِ فَإِنْ ضَرَبَ إِلَى اَلْخُضْرَةِ فَهُوَ مِمَّا لاَ يُؤْكَلُ وَ إِنْ ضَرَبَ إِلَى اَلْحُمْرَةِ فَهُوَ مِمَّا يُؤْكَلُ وَ إِنِ اِبْتَلَعَتْ حَيَّةٌ سَمَكَةً ثُمَّ رَمَتْ بِهَا وَ هِيَ حَيَّةٌ تَضْطَرِبُ فَإِنْ كَانَ فُلُوسُهَا قَدْ تَسَلَّخَتْ لَمْ تُؤْكَلْ وَ إِنْ لَمْ يَكُنْ فُلُوسُهَا تَسَلَّخَتْ أُكِلَتْ ".
Hadith.4162 - It has been narrated: "If someone finds a fish and does not know whether it is permissible to eat or not, then its tail should be split at the base. If the color turns green, it is not permissible to eat; but if it turns red, then it is permissible to eat.
And if a snake swallows a fish and then spits it out while it is still alive and wriggling, if its scales have peeled off, it should not be eaten; but if its scales have not peeled off, it may be eaten."