Aggression, especially territorial is a serious problem in farmed and ornamental fish. Especially the tropical species like Siamese fighting fish Betta splendens or marine species like blu head Thalassoma bifasciatum....Aggression, especially territorial is a serious problem in farmed and ornamental fish. Especially the tropical species like Siamese fighting fish Betta splendens or marine species like blu head Thalassoma bifasciatum. Also farmed species of Salmoniformes (Coho salmon Oncorhynchus kisutch, rainbow trout Oncorhynchus mykiss) exhibit territorial aggression which is correlated with growth rate of the fish. In these species native territorial aggression occurs, and in ethology it is called stereotypical agonistic behaviour or conspecific aggression. In this type modulation of aggression serotonin (5-HT) plays a main role. A decrease of 5-HT in brain intensifies these type of aggression and in opposite an increase of 5-HT reduces it. The purpose of this study was to examine the effects of different doses of fluoxetine on male aggressive behaviors of Betta splendens fish. It was concluded that fluoxetine added to aquarium water in the doses of 4, 40 and/or 100 μg·ga–1 BW during 14 - 28 days increased synaptic levels of 5-HT what in turn resulted in the reduction of the specific aggressive behaviors. Fluoxetine caused periodic, and sometimes even total weakening of male-male type fight, which is a standard trial applied in ethological research on Siamese fighting fish. In current study, the most effective was the dose of 40 μg·g–1 BW. The mechanism of this antiaggressivity depended on an increase of serotonergic system activity in animal brain (especially, in raphe nuclei), however synaptic levels of 5-HT in brain were not measured in this experiment. Thus, the hypothesis that exposure from day 1 - 21 would reduce aggression was rejected;as was the hypothesis that exposure on fluoxetine from day 10 (16) - 14 - 28 would rapidly reduce aggression in teleost fishes. The results obtained suggests that a complex role of serotonin in the expression of aggression in teleost fish because acute treatment with 5-HT1A receptor agonist WAY-100635 did not increase aggression in fish [1]. We emphasize the physiological concepts that can be addressed with this experiment, including the role of the serotonergic system in regulation of aggression, and the interplay of environmental contaminants and physiology in regulating the expression of behavior of fishes.展开更多
The physiological mechanisms underlying variation in aggression in fish remain poorly understood.One possibly confounding variable is the lack of standardization in the type of stimuli used to elicit aggression.The pr...The physiological mechanisms underlying variation in aggression in fish remain poorly understood.One possibly confounding variable is the lack of standardization in the type of stimuli used to elicit aggression.The presentation of controlled stimuli in videos,a.k.a.video playback,can provide better control of the fight components.However,this technique has produced conflicting results in animal behavior studies and needs to be carefully validated.For this,a similar response to the video and an equivalent live stimulus needs to be demonstrated.Further,different physiological responses may be triggered by live and video stimuli,and it is important to demonstrate that video images elicit appropriate physiological reactions.Here,the behavioral and endocrine responses of male Siamese fighting fish Betta splendens to a matched-for-size conspecific fighting behind a one-way mirror,presented live or through video playback,were compared.The video playback and live stimulus elicited a strong and similar aggressive response by the focal fish,with a fight structure that started with stereotypical threat displays and progressed to overt attacks.Postfight plasma levels of the androgen 11-ketotestosterone were elevated as compared to controls,regardless of the type of stimuli.Cortisol also increased in response to the video images,as previously described for live fights in this species.These results show that the interactive component of a fight and its resolution are not needed to trigger an endocrine response to aggression in this species.The study also demonstrates for the first time in a fish a robust endocrine response to video stimuli and supports the use of this technique for researching aggressive behavior in B.splendens.展开更多
文摘Aggression, especially territorial is a serious problem in farmed and ornamental fish. Especially the tropical species like Siamese fighting fish Betta splendens or marine species like blu head Thalassoma bifasciatum. Also farmed species of Salmoniformes (Coho salmon Oncorhynchus kisutch, rainbow trout Oncorhynchus mykiss) exhibit territorial aggression which is correlated with growth rate of the fish. In these species native territorial aggression occurs, and in ethology it is called stereotypical agonistic behaviour or conspecific aggression. In this type modulation of aggression serotonin (5-HT) plays a main role. A decrease of 5-HT in brain intensifies these type of aggression and in opposite an increase of 5-HT reduces it. The purpose of this study was to examine the effects of different doses of fluoxetine on male aggressive behaviors of Betta splendens fish. It was concluded that fluoxetine added to aquarium water in the doses of 4, 40 and/or 100 μg·ga–1 BW during 14 - 28 days increased synaptic levels of 5-HT what in turn resulted in the reduction of the specific aggressive behaviors. Fluoxetine caused periodic, and sometimes even total weakening of male-male type fight, which is a standard trial applied in ethological research on Siamese fighting fish. In current study, the most effective was the dose of 40 μg·g–1 BW. The mechanism of this antiaggressivity depended on an increase of serotonergic system activity in animal brain (especially, in raphe nuclei), however synaptic levels of 5-HT in brain were not measured in this experiment. Thus, the hypothesis that exposure from day 1 - 21 would reduce aggression was rejected;as was the hypothesis that exposure on fluoxetine from day 10 (16) - 14 - 28 would rapidly reduce aggression in teleost fishes. The results obtained suggests that a complex role of serotonin in the expression of aggression in teleost fish because acute treatment with 5-HT1A receptor agonist WAY-100635 did not increase aggression in fish [1]. We emphasize the physiological concepts that can be addressed with this experiment, including the role of the serotonergic system in regulation of aggression, and the interplay of environmental contaminants and physiology in regulating the expression of behavior of fishes.
基金supported by the Macao Science and Technology Development(FDCT)fund through projects 093/2017/A2 and 0025/2017/A2,and a postdoctoral fellowship FDCT0003/2019/APD awarded to SDC.
文摘The physiological mechanisms underlying variation in aggression in fish remain poorly understood.One possibly confounding variable is the lack of standardization in the type of stimuli used to elicit aggression.The presentation of controlled stimuli in videos,a.k.a.video playback,can provide better control of the fight components.However,this technique has produced conflicting results in animal behavior studies and needs to be carefully validated.For this,a similar response to the video and an equivalent live stimulus needs to be demonstrated.Further,different physiological responses may be triggered by live and video stimuli,and it is important to demonstrate that video images elicit appropriate physiological reactions.Here,the behavioral and endocrine responses of male Siamese fighting fish Betta splendens to a matched-for-size conspecific fighting behind a one-way mirror,presented live or through video playback,were compared.The video playback and live stimulus elicited a strong and similar aggressive response by the focal fish,with a fight structure that started with stereotypical threat displays and progressed to overt attacks.Postfight plasma levels of the androgen 11-ketotestosterone were elevated as compared to controls,regardless of the type of stimuli.Cortisol also increased in response to the video images,as previously described for live fights in this species.These results show that the interactive component of a fight and its resolution are not needed to trigger an endocrine response to aggression in this species.The study also demonstrates for the first time in a fish a robust endocrine response to video stimuli and supports the use of this technique for researching aggressive behavior in B.splendens.
