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To restore dam-blocked natural fish migratory passages, a growing number of artificial fishways have been built in water conservancy and hydropower projects in China. The Angu hydropower station involved diverse important fish habitats in the lower reaches of the Daduhe River in Southwest China. Therefore, a vertical slot fishway (VSF) and a nature-like fishway (NLF) were built near the backwater area of the reservoir to connect the upstream and downstream habitats. Hydrodynamic and aquatic ecological surveys were conducted after the completion of the project to estimate the fish passing effect of the two fishways. The results indicated that both fishways were in effective operation and could maintain the desired hydrodynamic conditions and be used by several local fish species. During the survey, 149 fish from 15 species and 111 fish from 17 species were captured by the traps in the VSF and NLF, respectively, while 1 263 fish from 27 species were found in the downstream area. Some species captured in the VSF were not found in the NLF, and vice versa, which implied the different preferences of fish. Meanwhile, 3 789 signals including 2 099 upward ones and 1 690 downward ones were monitored with an ultrasonic fish detector at the inlet of the VSF. These findings revealed the characteristics of fish species observed in and near the fishways and provided valuable insights into the different fish passing capabilities of VSF and NLF.

Leptin is a small peptide secreted by adipocytes and it plays important roles in regulating appetite, energy homeostasis, bodyweight, reproduction and immunity. However, its roles are still limited in teleosts. In the present study, a leptin gene was characterized from the darkbarbel catfish (Pseudobagrus vachellii) and its expression patterns in response to different feeding status were investigated. The cDNA of the pvleptin was 1186 bp long, containing a 519 bp open reading frame (ORF) that predicted to encode a protein of 172 amino acids. Multiple Leptins alignment showed that four a-helix domains and two cysteine residues were conserved in vertebrates. Three-dimensional (3D) structure modeling revealed that pvLeptin was highly conserved with that of other tetrapods. Genetic synteny analysis revealed that lepB had specifically lost in siluriformes teleosts. Phylogenetic analysis showed that fish lineage contained two clades of leptinA and leptinB, and the pvleptin was grouped into leptinA clade and shared a close relationship with its counterpart in P. fulvidraco. Tissue distribution analysis showed that pvleptin was widely distributed with the highest mRNA expression level in liver. Two-week fasting significantly decreased the transcription level while refeeding elevated the mRNA expression level of pvleptin in liver, suggesting leptin may be involved in regulating food intake and energy metabolism in darkbarbel catfish. These findings may expand our understanding about the evolutionary history and functional roles of Leptin in teleost, as well as lay a solid foundation for commercial production of darkbarbel catfish. [ABSTRACT FROM AUTHOR]