Hexavalent chromium [Cr(VI)] pollution is one of most serious heavy metal pollutants in the coastal area and posed serious threats to marine organisms and human beings. Many studies have been conducted on its toxicological effects on living organisms from morphological to physiological aspects. However, there are few studies about the transgenerational toxicological of Cr(VI). In this study, we exposed adult marine medaka fishes with Cr(VI) and their offspring with Cr(VI) to examine transgenerational effects of Cr(VI). We found that there were mechanisms such as changing reproduction modes in males to compensate for impacts on the reproduction. There were differences and similarities between the parental effect and the environmental effect, with the former one causing more serious adverse effects on the offspring of Cr(VI)-exposed fish. It was noteworthy that there was an interaction between the parental and offspring treatment which leads to the attenuation of the parental effects on offspring when the offspring also underwent the same treatment. In addition, physiological adaptation has also been observed in fish to improve their fitness. Overall, effects of Cr(VI) on fish and their offspring were studied to pave a way to study the of mechanisms of adaptation.

Although Mesogobio lachneri is the type species of the genus Mesogobio, its systematic position and status have remained unresolved to date. In this study, for the first time, we report the complete mitochondrial genome of M. lachneri using Sanger sequencing. It is a circular genome with a length of 16,602 bp, comprising 22 tRNAs, 13 protein-coding genes (PCGs), two rRNAs, and one non-coding control region. Our phylogenetic analysis reveals that M. lachneri is the close relative of the genus Gobio, indicating that Mesogobio may be a valid genus.

Belligobio pengxianensis is a small fish endemic to the upper Yangtze River of China. In this study, the complete mitochondrial genome of B. pengxianensis is determined for the first time, and it should become a reference sequence to aid in species identification, biodiversity monitoring and conservation. The mitogenome has overall length of 16,610 bp and AT content of 55.23%, including 13 protein-coding genes, two ribosomal RNAs, 22 transfer RNAs, and one non-coding control region. The results of phylogenetic analyses show that B. pengxianensis is nested within the genus Hemibarbus.