Specific Growth Rate

Specific growth rate (SGR) expresses growth as a percentage of body weight per day: SGR (% per day) = (ln W₂ − ln W₁) / (t₂ − t₁) × 100. Unlike absolute growth rate (g/day), SGR allows valid comparison of growth across different size classes, time periods, and species. Typical SGR values: Atlantic salmon parr 0.5–1.5%/day; tilapia fry 4–7%/day; newly hatched larval fish 15–30%/day. Temperature is the primary driver of SGR variation in aquaculture. SGR declines with increasing fish size.

SGR is used alongside FCR and condition factor to evaluate nutritional trials in aquaculture research.