This study evaluated the habitat coloration preferences of Siniperca chuatsi and Cirrhinus molitorella in both solitary (n = 1) and group (n = 3) settings across six colors. The results indicated that both individual and group S. chuatsi spent the majority of their time in and made frequent visits to the black area, followed by the blue area. While individual C. molitorella spent the majority of their time and visits in the blue region, groups showed a preference for the blue and white regions. These findings highlight the distinct habitat coloration preferences of S. chuatsi and C. molitorella in different group states, suggesting that habitat coloration has an important effect on fish behavior and environmental adaptation. From a behavioral ecology perspective, these preferences may be closely related to the survival strategies of fish. Notably, C. molitorella’s strong preference for blue and white backgrounds may reflect anti-predator behavior, helping C. molitorella avoid predators, such as S. chuatsi, in natural environments, thereby improving its chances of survival. This study provides a scientific basis for optimizing aquaculture environments, emphasizing the importance of considering habitat coloration and substrate type in designing environments to enhance fish welfare.

In this study, we assessed the growth patterns and population characteristics of the Odontobutis potamophila in Nansi Lake to inform evidence-based management recommendations for the sustainable development of fisheries in the region. A collection of O. potamophila was taken from Nansi Lake between August 2017 and July 2018 (except February) to estimate the age structure, growth pattern, and mortality of the population. Edge-type analysis of sagittal otoliths indicated that a single annulus was formed from March to May. The results revealed that the age structure of O. potamophila consisted of four age groups (0-3 ages), with 0-1 year-old fish comprising about 85.11% of the harvest. An isometric growth pattern was observed, with the Logistic growth function providing the best fit for combined sexes. SLt=172.94/(1+e−0.458(t−0.79))(n=591, R² = 0.622). Total mortality (Z), natural mortality (M), and fishing mortality (F) were computed as 1.69, 0.53, and 1.16/year, respectively. Meanwhile, the exploitation rate (E) was 0.69/year, in accordance with the rule of thumb (E>0.5, the fish stock was undergoing overfishing), which indicated the stock has been overfished slightly. These results showed that brief generation-time, dominance of juvenile fish and relatively high natural mortality of the O. potamophila provide essential information on the native fish species in Nansi Lake, which may be essential for conservation strategies and artificial propagation. At the same time, these results provide critical data for sustainable fisheries management in Nansi Lake and similar ecosystems.

The Geheyan Reservoir, located on the Qingjiang River, a tributary of the Yangtze River, is important for regional water supplies and ecological conservation. Understanding changes in ecosystem structure and function has become critical for assessing efficacy after the implementation of a fishing ban. This study employs the Ecopath model to examine the ecosystem characteristics of the Geheyan Reservoir before (2017) and after (2022) the fishing ban. The results show significant differences in trophic levels, energy transfer efficiency, and ecosystem maturity between the two periods. The trophic levels increased from 3.36 pre-fishing ban to 3.89 post-ban, indicating an enhanced complexity in the food web structure. The highest eco-trophic efficiency for major commercial fish species increased after the ban, indicating improved energy utilization efficiency. However, energy transfer bottlenecks were still observed between trophic levels II and IV, suggesting ongoing challenges in nutrient cycling. The total primary production-to-total respiration ratio (6.93) and the connectivity index (0.25) indicate that the ecosystem’s maturity and stability have improved after the fishing ban. These findings underscore the ban’s effectiveness and provide a scientific foundation for sustainable management of Geheyan Reservoir and similar ecosystems in the Yangtze River Basin.

The color preference of juvenile bronze gudgeon (Coreius heterodon), an endemic fish species in the Yangtze River, remains poorly understood despite its importance in animal welfare and aquaculture. In this study, color selection behavior was assessed across 6 background colors (red, yellow, blue, green, black, and white) under both isolated and grouped social conditions, using a 6-arm radial maze. The results reveal that juvenile C. heterodon exhibit a strong and consistent preference for yellow–green backgrounds and distinct avoidance of black–red, regardless of social context, with these behaviors likely rooted in early imprinting, that is, fixed responses formed without the need for subsequent reinforcement. Social condition was found to modulate responses to white and blue, shifting white from slightly attractive to neutral/aversive and blue from aversive to attractive. These findings directly inform aquaculture practice, suggesting that establishing yellow–green substrates while minimizing black–red areas is advisable. Presumably, prerelease acclimatization based on imprinting mechanisms would shorten natural acclimatization time and enhance poststocking survival. Our findings provide a scalable, behaviorally informed framework for optimizing welfare and production in C. heterodon and related species.