Peace be upon you. According to Sayyid Kazem al-Haeri, there are two conditions for the permissibility of eating fish:
1. It must have scales.
2. The fisherman must catch it alive; if it dies in the fishing net, it is forbidden to eat.
Regarding the first condition, it is usually met if the fish is not skinned. However, if it is skinned, as in the case of canned fish, it can be permissible if the label indicates that it is a type with scales, such as tuna or sardines, and if the exporting country adheres to strict regulations regarding the specifications stated on the label.
As for the second condition, if there is no certainty that the fish was alive when caught, it is not permissible to eat it.
Source: [Sayyid Kazem al-Haeri's website](
https://gusercontent.xcdn.app/.webcache/search?q=cache:1qk1paeA69AJ:www.alhaeri.org/pages/qa-detail.php%3Fcid%3D71+&cd=1&hl=en&ct=clnk&gl=lb)
Additionally, regarding the opinions of Sayyid Sistani and Sayyid Khamenei, may Allah preserve them, you can refer to this link: [Eating Tuna](
https://www.islamq2a.com/544/?show=544#q544).
May you be successful in all good.