For IgAN patients with stage 3 kidney disease, raw fish (even frozen) isn't recommended due to:

1. Risk of foodborne illness - compromised kidneys are more vulnerable
2. Higher phosphorus content in raw fish
3. Potential bacterial contamination

Instead, thoroughly cook fish to make it safer while still getting omega-3 benefits. Always consult your nephrologist about specific dietary choices, as individual recommendations may vary based on your lab values and symptoms.