Summary:
- Researchers have discovered that the largest group of freshwater fish, the catfish, actually originated in the ocean, not in rivers as previously believed.
- Genetic analysis of various catfish species shows that their common ancestor was a marine fish that later adapted to live in freshwater environments.
- This surprising finding challenges the long-held assumption that freshwater fish evolved from their ancestors in rivers and lakes, and provides new insights into the evolutionary history of these diverse and important aquatic creatures.