Octopuses (Eledone cirrhosa (Octopoda: Cephalopoda)) held in an aquarium were subjected to varying conditions of feeding and starvation to evaluate putative indices of feeding and growth. Specific growth rate (%d−1) was linearly related to feeding rate (% of the body mass d−1) in animals with a mean body mass of 250 g at 15°C. Maximum growth rates varied between > 2% d−1 (body weights < 300 g) to < 1% d−1 (body weights ≤ 900 g) but specific growth rates were not related to body weight. Growth rates became negative (weight loss) after one week without food.
The digestive gland index (DGI) was significantly correlated with short and long-term feeding and specific growth rates, and with body weight. Muscle RNA concentration was linearly correlated with growth rate during the previous 1–3 weeks but not with feeding rate. RNA:protein ratios were not different between mid-arm and mantle sample sites but arm tip values were significantly higher. RNA:protein ratio was related to body weight only in feeding animals. It is concluded that DGI is an index of feeding rate and that RNA:protein ratio can be used as an index of recent (~ 4 weeks) growth rate.