Study on Organogenesis and Histology of Siamese Fighting Fish, Betta splendens Regan

Abstract

A study on organogenesis and histology of Fighting fish fry was conducted. The fry developed to fingerling size within 15 days after hatching. The development and formation of the organs of Siamese fighting fish fry from day 1 to day 30 are described. Yolk sac was reabsorbed within day 4 after hatching. The nervous system including the brain, ears, spinal cord ect, was well developed in comparison to the other systems of the fry at same age. It was almost completely developed into different parts when the fry was 2 days old. The heart of 1-day fry was the blood chamber and it developed into the complete four chambers at the age of 8 days. The digestive tract was developed as a long blind tube from day one and became fully formed as the one in adult around day 15. Exocrine pancreas and spleen were forming by day 3 and 5, respectively. The skeletal muscle blocks were separated from each other by the myoseptum. They quickly expanded in volume. Thyroid gland and thymus gland were observed around day 7 and day 8, respectively. The labyrinth organ was found at the anterior area of opercular chamber by day 9. Around day 15, gonads were differentiated into ovary or testes.