Farmed fish face persistent challenges arising from diverse environmental factors and human activities, which induce both acute and chronic stress responses, thereby increasing their susceptibility to diseases and mortality. Therefore, it is essential to comprehend the stressors and corresponding stress responses in fish to recognize and mitigate harmful stress during aquaculture practices. In this review, we provide an overview of the various stressors present in aquaculture, along with the resultant alterations in neuroendocrine responses, including the brain–sympathetic–chromaffin cell (BSC) axis, hypothalamus–pituitary–interrenal (HPI) axis, and caudal neurosecretory system (CNSS), as well as neurotransmitter levels within the nervous system, experienced by fish under different types of stress. Fish possess well-developed nervous and endocrine systems that respond to stress, with complex communication networks among these systems demonstrating distributed collaboration. An understanding of the neuroendocrine and neurotransmitter responses to stress may enhance our comprehension of fish stress mechanisms and facilitate the development of an integrated dietary supplementation strategy and improve their resilience against the diverse stresses encountered in aquaculture.

In the artificial breeding of Pampus argenteus (Euphrasen, 1788), female fish spawn before male release sperm, which indicates rapid ovarian development. In fish, aromatase is responsible for converting androgens into estrogens and estrogen plays a crucial role in ovarian development. In this study, we aimed to investigate the potential role of brain-type and ovarian-type aromatase to study the rapid ovarian development mechanism. The results showed that cyp19a1a was mainly expressed in the ovary and could be classified as the ovarian type, whereas cyp19a1b could be considered as the brain type for its expression was mainly in the brain. During ovarian development, the expression of cyp19a1a in the ovary significantly increased from stage IV to stage V and Cyp19a1a signals were present in the follicle cells, while cyp19a1b expression in the pituitary gland decreased from stage IV to stage V. To further investigate the function of Cyp19a1a, recombinant Cyp19a1a (rCyp19a1a) was produced and specific anti-Cyp19a1a antiserum was obtained. The expressions of cyp19a1a, estrogen receptors 2 alpha (esr2a), and androgen receptor alpha (arα) were significantly upregulated in the presence of rCyp19a1a. Meanwhile, cyp19a1a was expressed significantly after E2 treatment in both ovarian and testicular tissue culture. Taken together, we found two forms of aromatase in silver pomfret. The ovarian-type aromatase might play an important role in ovarian differentiation and maturation, and participate in E2 synthesis through co-regulation with esr2a. The brain-type aromatase cyp19a1b might be involved in the regulation of both brain and gonadal development.