Comparison of growth and survival rates of big blue octopus (Octopus cyanea, 1849) fed on natural and formulated diets in captivity

Comparative studies on growth and survival rates of Octopus cyanea fed on natural and formulated diets in captivity have never been conducted in Tanzania. This study aimed to investigate the growth and survival rates of O. cyanea using natural and formulated diets. The three formulated diets were made up of a mixture of sardines, fish waste, and alternating ratios of crab paste content across the different diet treatments. Treatment B had 75 % crab paste content, Treatment C had 50 % crab content and Treatment D had 0 % crab content while Treatment A was based on a natural diet of frozen crabs (Scylla serrata) and was used as a control. After five weeks of feeding, the effect of each diet was analyzed on growth performance and survival rates for the octopus. Results showed that there was a significant difference in growth rate in all the diet treatments (H=13.243, p=0.004, DF=3). Specific growth rates (SGR) were higher in octopuses fed in feed treatment A and lowest in feed treatment D. The survival rates were 100 % for treatment A and feed treatment B and 75 % for treatments C and D respectively. More research is needed to develop optimal nutritional diets for faster growth rates of O. cyanea in captivity.