Throughout the current study, sampling of Callistoctopus macropus was achieved monthly from January to December 2019. The study examined various biological characteristics, including sex ratio, fertility, length at first maturity, maturity stages, gonado-somatic index, hepato-somatic index and fecundity. The fecundity of Callistoctopus macropus was addressed; the number of the eggs ranged between 205682 eggs for females, with an average mantle length of 8.5cm to 61946 eggs for females, with an average mantle length of 14.5cm; they were observed to be fertile. Fecundity generally rose with increasing mantle length, yet there were dissembled differences in the fecundity of the same female mantle length. For males and females, the length values at the initial maturity were 7.8 and 8.3cm, respectively. There are four stages of maturity for females: immature, maturing, ripe and spent in addition to three stages for males: immature, ripe and spent. From March to July, there were plenty of ripe males; and from March to August, there were enough females. According to the gonado-somatic index data, the female's spawning season lasts from June to October, whereas the male's spawning season is from June to September. Hepato-somatic index data values for both sexes reach their peak before the spawning season, however, during the spawning season, the lowest values were noted. These could result from the digestive gland's lipid reserves being depleted over the protracted spawning and breeding season. Males outnumber females throughout the year except March and August. The ratio between males to females was 1.8:1.