Aeromonas schubertii
is a Gram-negative, rod-shaped bacterium. It is a rare species that has been reported in humans and aquatic animals. Here, we report the genome sequences of
A. schubertii
strains isolated from two mass mortality events in central Thailand that were associated with aquaculture of Asian seabass.
The Japanese flathead, Inegocia japonica Cuvier, 1829 is a commercially important fish in small‐scale coastal fisheries in Thailand; however, an explanation of its digestive biology is missing. This study describes the digestive tract and accessory organs of I. japonica, using morphological and histological methods. The fish (10 individual fish, 24.5 ± 0.98 cm in total length) were obtained from Libong Island, Thailand. Integrated morphological and histological data showed that the digestive tract was composed of oesophagus, stomach, pyloric caeca and intestine, with accessory organs. All digestive tracts consisted of four layers, including mucosa, submucosa, muscularis and serosa. Two stomach regions were identified (cardiac and pyloric stomachs). Several clusters of gastric glands were identified in the cardiac stomach. Each gland was a unicellular structure. The apical surface of this gland contained the vacuolar cell. The intestine was lined with a simple columnar structure with goblet cells that was similar to pyloric caecum. Goblet cells were rare in the anterior intestine, in contrast to the posterior intestine where goblet cells were abundant. The numerous of hepatocyte was mostly observed in the liver, whereas an exocrine acinar cell of pancreas was also identified. The results of our observations provided the first information of the digestive tract of I. japonica and can be applied to advanced study, such as physiology and histopathology.
Light is a key environmental factor that is strongly related to fish activity and behavior. Exposure to certain wavelengths is known to affect growth performance and survival of teleost larvae and juveniles. Our study aimed to determine the effects of exposure to three light sources [red (710 nm), blue (453 nm) and green (510 nm)] on growth performance, behavioral response, visibility (time to eat, in minutes), and the structure of the retinal layer in juvenile [approx. 4.3 cm in total length (N = 30)] seabass (Lates calcarifer). Fish were acclimated to the three light conditions for four weeks prior to data collection. Behavioral responses, including schooling organization, swimming speed, time to consume prey, and feeding response, were all improved in juveniles reared under red light (710 nm). Preliminary histological observations revealed that fish from the red-light environment have the thickest retina layers and the highest density of photoreceptors. Our data suggest that red light is useful in the aquaculture of juvenile L. calcarifer.
The activity of the sensory organ in the eye structure of the teleost fish is essential as it plays an important role in regulating fish-feeding behaviours. Unfortunately, the above information of zebra-snout seahorse Hippocampus barbouri, an aquaculture species in Thailand, has not been described. In this study, the eye structure, together with the retinal structure of juvenile [5th and 20th day after birth (DAB)] and adult (35th DAB), H. barbouri reared in captivity was investigated. All DABs were carried out and histologically observed. Light microscopic level explored the external-lateral surface of eye structure of H. barbouri, which consisted of the external, middle, and inner layers, as similarly reported in other teleost species. A well-differentiated retinal and photoreceptor cell layer were observed at 35th DAB compared to that at other DABs. This feature might be adequate to support the base of the increased feeding activity of adult seahorse in captivity for further research.
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