Neuropeptide Y family (NPY) is a potent orexigenic peptide and pancreatic polypeptide family comprising neuropeptide Y (Npy), peptide YYa (Pyya), and peptide YYb (Pyyb), which was previously known as peptide Y (PY), and tetrapod pancreatic polypeptide (PP), but has not been exhaustively documented in fish. Nonetheless, Npy and Pyy to date have been the key focus of countless research studies categorizing their copious characteristics in the body, which, among other things, include the mechanism of feeding behavior, cortical neural activity, heart activity, and the regulation of emotions in teleost. In this review, we focused on the role of neuropeptide Y gene (Npy) and peptide YY gene (Pyy) in teleost food intake. Feeding is essential in fish to ensure growth and perpetuation, being indispensable in the aquaculture settings where growth is prioritized. Therefore, a better understanding of the roles of these genes in food intake in teleost could help determine their feeding regime, regulation, growth, and development, which will possibly be fundamental in fish culture.

In vertebrate the development of gonad into testis or ovary requires the combined effect of genes and hormones to trigger differentiation from a bipotential gonadal primordium. Knowledge of the gonad development process is vital in studies on fish sex determination and differentiation. The spotted scat (Scatophagus argus) is an economically important marine fish with an XX/XY sex-determining system and exhibits sexual growth dimorphism in favor of females. Meanwhile, information on gonad development and gene expression patterns in the early gonads is unknown. This study explores the pattern of spotted scat early gonad development by morphological and molecular means. In the undifferentiated gonads, the number of germ cells in females is not significantly different from males. At age 3 mph (months post-hatch), the number of germ cells in females was significantly higher than in males. The sex differentiation began in females before males with the proliferation of primary oocyte and spermatocytes at 3.5 and 4 mph, respectively. In the early gonads, dmrt1 and amh were significantly higher in XY-fish, while cyp19a1a and foxl2 were higher in the XX-fish. Within the critical period of sex differentiation, estradiol treatment was able to sex-reverse XY-male to XY-female. In the sex-reversed group, male (dmrt1 and amh) and female (cyp19a1a and foxl2) related genes were suppressed and increased, respectively. 17α-Methyltestosterone or aromatase inhibitor (letrozole) could not induce sex reversal in XX-fish due to the absence of the male-specific dmrt1 required for testes development. Conclusively, this study identifies the critical window for sex differentiation and significantly higher germ cell numbers in future females than males. We provide evidence that the phenotypic XY-male is reversible, while the phenotypic XX-female is irreversible. Dmrt1 is necessary for testis differentiation, amh in males, and cyp19a1a and foxl2 in females could also be used as molecular markers in early gonads. This study explicitly presents valuable information for research development on sex determination and differentiation and sex control in spotted scat.

Neuropeptide Y (Npy) is an intricate neuropeptide regulating numerous physiological processes. It is a highly conserved peptide known to improve feed intake in many vertebrates, including fishes. To enlighten the mechanism of Npy in spotted scat feed intake control, we cloned and identified the Npy cDNA sequence. We further examined its expression in some tissues and explored its expression effects at different time frames (hours and days). Here, we discovered that spotted scat Npy comprised a 300 bp open reading frame (ORF) and a 99 amino acid sequence. Npy was identified to be expressed in all tissues examined. Using in situ hybridization examination, we proved that npy has a wide expression in the brain of the spotted scat. Furthermore, the expression of npy in the hypothalamus significantly increased one hour after feeding (p < 0.05). Further, it was revealed that npy expression significantly increased in fish that were fasted for up to 5 days and significantly increased after refeeding from the 8th to the 10th day. This suggests that Npy is an orexigenic peptide, and hence, it increases food intake and growth in the spotted scat. Additionally, results from in vitro and in vivo experiments revealed that Npy locally interacts with other appetite-regulating peptides in the spotted scat hypothalamus. This research aimed to set a fundamental study in developing the feed intake regulation, improving growth and reproduction, which is significant to the aquaculture industry of the spotted scat.

With the aim of reducing the cost of ovaprim in induced breeding, the present study was conducted to evaluate the use of diluted ovaprim with normal saline solution at levels of 0% (control), 25%, 50%, 75% and 100% in the induced breeding of Clarias gariepinus. Ten gravid female and ten matured male CG were obtained from the Pilot Aquaculture Centre (weight range of 500 g-1000 g). In all, ten (10) spawning tests were conducted. Females under each treatment were injected around the dorsal fin and after close to 24 hours, each female was stripped of her eggs, total number of eggs A-12982 (40.2 g), B-12659 (39.2 g), C-12336 (38.2 g), D-0 (0 g) and E-0 (0 g). After twenty-four hours of the incubation period, total number of hatched eggs were determined and the unfertilized eggs that turned whitish were determined using the volumetric counting method. The percentage of hatchability of stripped eggs was A-65% (6299), B-62% (6008) and C-69% (6686), with no noteworthy (P > .05) among the three treatments, whereas percentage survival of the fry was 3124 (49.6%), 2644 (44%) and 3610 (54%) for A, B, and C treatments respectively. From the findings of our research, the study recommends the use of treatment C in induced breeding of catfish.