DOI: 10.3897/zoologia.36.e31791

Authors: Mohd Y. Bhat, Ashok Channa, Bilal A. Paray, Mohammed K. Al-Sadoon, Irfan A. Rather

Abstract: The present study aimed to investigate the macroscopic structure of the gastrointestinal tract (GIT) of Schizothorax esocinus Heckel, 1838. The surface architecture of the buccopharynx, oesophagus and the entire intestinal tract of S. esocinus has been examined under scanning electron microscope (SEM) after fixing in 2.5% glutaraldehyde buffered with 0.1 M sodium cacodylate at pH 7.3 for 18–48 hours and post-fixation for two hours at room temperature in 1% osmium tetra oxide buffered at pH 7.3 with 0.1 M cacodylate. The mucosal surface of buccopharynx, esophagus, intestinal bulb, and intestine reveal prominent longitudinal major or primary mucosal folds which are further subdivided into the series of irregular and well-circumscribed folds called minor or secondary folds. However, in the intestinal bulb and intestine, the longitudinal major or primary folds themselves form wavy or zigzagging patterns along the mucosal surface. The fine structure of the surface epithelium further shows that the apical surfaces of the epithelial cells are ped with finger-print like microridges, arranged in various patterns and regularly spaced. The rectal mucosa, on the other hand, displays a highly irregular type of major mucosal folds. The separation can’t be seen between major mucosal folds. A thin film of mucous spread over the mucosal folds and the numerous pores through which mucous cells release their content has also been noted along the rectal mucosa. This investigation suggests the possible role of different digestive organs in relation to feeding, digestion, storage, absorption, and various other physiological processes, thereby providing a knowledge necessary to the understanding of pathological or physiological alterations in both aquaculture and natural environment.

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DOI: 10.3897/zoologia.35.e22162

Authors: Dongmei Zhu, Kun Yang, Ning Sun, Weimin Wang, Xiaoyun Zhou

Abstract: The topmouth gudgeon, Pseudorasbora parva (Temminck & Schlegel, 1842), is a small cyprinid fish that inhabits the littoral zones of freshwater habitats throughout Asia and Europe. It is regarded as an invasive species in Europe, but in its native range, in China, as food and as an environmental bio-indicator. In this study, the embryonic and larval development of P. parva was investigated for the first time. The eggs of P. parva are transparent, adhesive and elliptical. The mean size of fertilized eggs was (1.63×1.31) ± 0.04 mm. From fertilization to hatching, embryonic development could be divided into eight stages and 34 phases, and the incubation period lasted for 109.25 hours at 24 ± 1 °C. Newly hatched larvae were 4.1 ± 3 mm in length, and the yolk absorption was completed within six days after hatching. The first and second swim bladders formed at the third and ninth day, respectively. The pectoral fin formed before the hatching stage, followed by the caudal, dorsal, anal and ventral fin formation after hatching. About 20 days after hatching, the morphology of the fry was similar to the adult fish. These findings provide a basis for determining the complete ontogeny of P. parva, as well as facilitate the management and utilization of this fish.

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