This is a reference to a report by Jaʿfar al-Ṣādiq where he is asked about the permissibility of consuming an eel-like fish (jirrī/jirrīth); al-Ṣādiq states that eating it is impermissible based on the view of ʿAlī b. Abī Ṭālib. Hossein Modarressi cites this reference to argue that, contrary to reports found in some Sunnī works that claim that ʿAlī agreed with others on the lawfulness of eating jirrī, reports from al-Ṣādiq and his father al-Bāqir challenge the validity of this attribution.
This source is part of the Online Companion to Hossein Modarressi, Text and Interpretation: Imam Jaʿfar al-Ṣādiq and His Legacy in Islamic Law (Harvard University Press, 2022).