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In order to study the effects of body color and social familiarity on the shoal selection in cichlids, Sciaenochromis fryeri with a blue body color, was selected as the study object. White Hindongo socolofi and yellow Labidochromis caeruleus were chosen as stimuli to test whether experimental fish displayed a preference for specific color phenotypes, considering the controlled social familiarity of the shoal. Additionally, the study aimed to determine if experimental fish exhibited a preference for associating with shoal stimuli possessing a preferred color phenotype but were unfamiliar to the shoal. The results showed that when there was no difference in the social familiarity of shoal stimuli, both individuals and groups demonstrated a preference for associating with shoals of the preferred color phenotype. However, when stimulating fish with different social familiarity, individual S. fryeri showed an association with the more socially familiar shoal, while group experimental fish displayed a preference for the shoal with the preferred color shoal phenotype. The study show that body color exerts a greater influence on shoal selection than social familiarity. Body color emerges as a potentially significant shoal cue for cichlids, providing a foundation for exploring the ecological effects of body color (such as predator-prey interactions) within fish shoals. [ABSTRACT FROM AUTHOR]

To investigate the effects of starvation on visceral organs and excess post-exercise oxygen consumption (EPOC) of juvenile common carp (Cyprinus carpio), the body mass and body length of 35 fish with (21.34±0.42) g and (9.39±0.08) cm were randomly divided into 5 groups, i.e., control group (S0), 1 week starvation group (S1), 2 week starvation group (S2), 4 week starvation group (S4) and 8 week starvation group (S8). The results indicated that body mass, carcass mass, visceral mass, liver mass, digestive tract mass, heart mass and gill mass of juvenile C. carpio significantly decreased with the increased starvation period. Starvation have no effect on the body length, heart and gill indexes of C. carpio (P>0.05). Carcass index significantly increased in S2, S4 and S8 groups compared to those in S0 and S1 groups (P<0.001). Viscus and liver indexes significantly decreased in S2, S4 and S8 groups compared to those in S0 and S1 groups (P<0.001). The digestive tract index in S1 group was significantly lower than that of S0 group, but was significantly higher than those of S2, S4 and S8 groups (P<0.001). Pre-exercise metabolic rate in S1 group was significantly lower than that of S0 group, but was significantly higher than those of S2, S4 and S8 groups (P<0.001). The peak post-exercise metabolic rate and increment of metabolic rate in S1 group were significantly higher than those of S0, S4 and S8 groups (P<0.001, P=0.003). There was no significant difference in the time to MO2 peak of C. carpio among group (P>0.05). Factorial scopes in starved groups were significantly higher than that of S0 group (P=0.002). The magnitude of EPOC in S1 group was significantly higher those of S4 and S8 groups (P=0.043). Our results suggested that organs/tissues responded differently to starvation due to the different physiological roles, and that short-term starvation significantly increased aerobic and anaerobic capacity to improve feeding and escaping ability in juvenile C. carpio. [ABSTRACT FROM AUTHOR]