The minimum viable population (MVP) size has been compared for a wide range of organisms in conservation biology, but a limited number of studies investigated it for freshwater fishes, which exhibit diverse life history strategies. In this study, the MVP size and population growth rate of 36 fish species in the Yangtze River were estimated and compared with their life-history traits. The results indicated that the MVP size ranged from 42 to 320 individuals, and instantaneous per-capita population growth rate ranged from 0.009 to 0.188 per year. MVP size and population growth rate were significantly associated with three life history traits: the age at maturity, generation time, and fecundity. Long-lived species with delayed maturation, long generation time, and high fecundity had a greater MVP size and a lower population growth rate than short-lived species. Therefore, our results emphasize a need for prioritizing our conservation effort more on long-lived species.

Coral reefs are known as “tropical rain forests” in the ocean. Fish diversity is extremely high, accounting for one-third of marine fishes. To better protect and manage coral reef fishes, this study systematically compiled documents and databases published in China. We counted 2855 species of coral reef fishes in China, which belong to 3 classes, 41 orders, 252 families, and 1017 genera. Among these, Perciformes was the dominant order, accounting for 57.31% of the total species. Gobiidae (7.43%), Labridae (5.36%), Pomacentridae (4.52%), and Serranidae (4.38%) were the main families, while other families accounted for less than 4%. Furthermore, 5.56% of coral reef fish species have entered the IUCN Red List. The present study found that coral reef fishes can be divided into nearshore and offshore. This was mainly because the nearshore coral reef fishes were more affected by human disturbance and runoff from the mainland, whereas offshore coral reef fishes were in areas with high salinity and temperature far from the mainland, where human disturbance was less. Coral reef fish species’ diversity had a significant positive correlation with coral species diversity (p < 0.05), mainly because corals provide habitat and shelter. This study is the first systematic compilation and analysis of coral reef fishes in China and provides a basic reference for global protection management and biological geographical analysis.

Mangroves are among the most productive marine and coastal ecosystems and play an important role in maintaining the stability and diversity of fish communities. To explore the structure of mangrove fish communities in China, we compiled previous studies, monographs, and two databases on 54 mangrove areas published in the past 30 years. Mangrove fish communities in China comprised Osteichthys (597 species) and Chondrichthyes (14 species), representing 611 species in 344 genera, 117 families, and 28 orders. Perciformes were the predominant taxon, with 350 species in 52 families, accounting for 57% of the total species richness. Reef fish accounted for 29.62%. With regard to feeding groups, there were 328 carnivorous species (53.68%), 214 omnivorous species (35.02%), 41 herbivorous species (6.71%), and 28 detritivores species (4.58%). Classified by body size, 57.61% were small-sized, 24.22% medium-sized, and 18.17% were large-sized fishes. A total of 5.23% (32 species) of these mangrove fish are currently on IUCN red lists, i.e., 2 species are critically endangered, 4 are endangered, 12 are vulnerable, and 14 are near threatened. Cluster analyses shows that Chinese mangroves fish were divided into two categories, i.e., coastal mangrove and island mangrove type. This is closely related to the distribution of reef fish. Moreover, the number of fish species showed a strong positive correlation with mangrove area, but not with latitude. The main reasons may be the subtropical and tropical geographic locations, as well as the characteristics of the South China Sea and the Taiwan Warm Current. The size and integrity of mangrove area are crucial to the local ecosystems; thus, protecting and restoring mangroves is of great significance to large-scale ecosystem-stability and local biodiversity.

To understand the molecular mechanisms and adaptive strategies of holocentrid fish, we sequenced the mitogenome of eight species within the family Holocentridae and compared them with six other holocentrid species. The mitogenomes were found to be 16,507–16,639 bp in length and to encode 37 typical mitochondrial genes, including 13 PCGs, two ribosomal RNAs, and 22 transfer RNA genes. Structurally, the gene arrangement, base composition, codon usage, tRNA size, and putative secondary structures were comparable between species. Of the 13 PCGs, nad6 was the most specific gene that exhibited negative AT-skews and positive GC-skews. Most of the genes begin with the standard codon ATG, except cox1, which begins with the codon GTG. By examining their phylogeny, Sargocentron and Neoniphon were verified to be closely related and to belong to the same subfamily Holocentrinae, while Myripristis and Ostichthys belong to the other subfamily Myripristinae. The subfamilies were clearly distinguished by high-confidence-supported clades, which provide evidence to explain the differences in morphology and feeding habits between the two subfamilies. Selection pressure analysis indicated that all PCGs were subject to purifying selection. Overall, our study provides valuable insight into the habiting behavior, evolution, and ecological roles of these important marine fish.