The Morphological and Histological Developmental Study of the Gastrointestinal Tract of Peres Fish (Osteochilus kappenii) Larvae.

Peres fish (Osteochilus kappenii) is a native freshwater fish in Central Aceh, Indonesia. This study aimed to determine the morphology and histology development of the digestive tract of Peres larvae. Understanding the developmental stages is essential to support the success of larval rearing during ontogeny. The parameters observed include the total length (TL) of larvae, daily growth rate, larval morphology, and histology of the digestive tract. Furthermore, the total length of the larvae was measured from 1 to 25 day after hatching (DAH). The larvae sampling was conducted at 1, 2, 3, 4, 8, 10, 15, 20, and 25 DAH. Morphological and histological observations were carried out microscopically, and data were analyzed descriptively. The results showed that the TL of larvae growth at the beginning (1 DAH) and termination (25 DAH) of the study was 4.58 ± 0.24 mm and 9.62 ± 0.79 mm, respectively. Based on the structural development of the body and food sources, the development of percussion larvae was divided into four phases, namely the yolk sac (0-4 DAH), pre-flexion (5-15 DAH), flexion (16-20 DAH), and post-flexion (21-25 DAH). The yolk was completely absorbed 4 DAH, marking the end of the yolk sac phase, as the Peres fish larvae began to use external feed. At 25 DAH, the larval morphology was fully formed and pigmentation spread throughout the body. The digestive organs and glands are well-developed with differentiation of the midgut and hindgut, increased goblet cells in the intestine, and increased lipid vacuoles in the liver and zymogen in the pancreas to utilize feed optimally. [ABSTRACT FROM AUTHOR]