ShuiEro ... from vague up to sometimes ;) crystal clear drop by drop ...

The round-tailed paradise fish (Macropodus ocellatus) is important to the local ecosystem and economy. Other species in the genus Macropodus are undergoing population declines, indicating that the M. ocellatus population might also be declining. Therefore, the status of M. ocellatus, related to standing-water ecosystem stability and sustainable utilization of fishery resources, requires attention. In this study, we assessed the spatial pattern of the M. ocellatus genetic structure in 10 localities from China. Sequencing of Cytb (1135 bp) and the D-loop (668 bp) yielded 26 and 10 haplotypes, respectively. A total of 30 haplotypes were identified among 165 concatenated mitochondrial DNA sequences. The results showed that the total haplotype diversity of the 10 populations is high (0.910) and that genetic diversity indices for sequences from HuaiAn were the highest (haplotype diversity Hd = 0.780, nucleotide diversity pi = 0.00363). The results of AMOVA indicated that most genetic variation was among populations within groups (80.22%, P < 0.001). The XinXiang and TangShan (TS) groups showed mild genetic differentiation (Fst = 0.022), whereas all other groups showed high genetic differentiation (P < 0.05). Based on gene flow analysis, HuangGang and TS were found to frequently communicate (Nm = 15.837). WuXin had the highest haplotype diversity and highest genetic divergence from other populations, and thus, it should be managed as an independent group. These findings provide novel insights for the improved germplasm management and cultivation of M. ocellatus.