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Metabolism
Fish Growth
Unlike mammals, most fish grow indeterminately - their bodies keep adding cells throughout life, so an old individual is much larger than a young one of the same species.
System: Muscular Level: Beginner Discipline: Physiology
📖 Overview
Fish growth is one of the great features distinguishing them from mammals. In fish, muscle fibers keep adding new cells (hyperplasia) throughout life - not just enlarging existing ones. This is why old fish can reach enormous sizes: 100-year-old rockfish, 200-year-old sturgeon. Growth rate depends on temperature, food, and stress; hormonal regulation is via growth hormone and IGF-1.
🔑 Key Concepts
Indeterminate growth, hyperplasia vs hypertrophy, growth hormone axis, condition factor, K-selected vs r-selected life history.
✨ Fun Fact
The oldest documented rougheye rockfish was 205 years old - a fish that hatched when Napoleon was on the throne of France.