Metabolic costs of aggressive behaviour in the Siamese fighting fish,Betta splendens

Aggressive conflicts between males are often resolved by means of multiple ritualized agonistic displays without damaging escalation. Apparently, in such cases by using those displays opponents exchange important motivational and physical information on which they base a decision to stay or leave the interaction. In the Siamese fighting fish, the time spent spreading the dorsal fin and erecting the gill coverts predicts who will be the winner or loser of the interaction. Two experiments were carried out to study whether display performance might be costly. First, oxygen consumption was measured during mirror‐image stimulation. This experiment showed that oxygen consumption was positively correlated with gill cover erection and dorsal fin spread. In the second experiment, a fight between two opponents was simulated and the oxygen consumption of the expected winner and loser was compared. Metabolic rates were not different between winners and losers before and during the fight, but winners showed higher oxygen consumption in the night after the fight. These results are in accordance with costs of display performance and with long‐lasting physiological consequences of winning or losing a fight. Aggr. Behav. 32:1–7, 2006. © 2006 Wiley‐Liss, Inc.     

Social organization and aggression within small groups of female siamese fighting fish,betta splendens

Small groups of female Siamese fighting fish were observed in an attempt to determine whether a dominance order exists in these fish. Each fish, in each group, was allocated a rank for each activity on each day of observation. The rankings for the number of bites of food from a restricted source, the number of displays, the order of attacks, and the number of attacks each showed a significant concordance from day to day. A significant concordance was also found between the rankings of the different parameters. These data show that a stable dominance order is formed when females are in small groups. The top-ranked fish engages in more mutual displays and single-fish displays with the second-ranked fish than with the bottom-ranked fish. Displays showed differences in duration dependent upon whether or not they resulted in an attack. These data are discussed in terms of the conflict hypothesis and are in agreement with Simpson [1968] concerning the use of that hypothesis.     

Visual reinforcement in the female Siamese fighting fish, Betta splendens

Operant conditioning with Betta splendens (Bettas) has been investigated extensively using males of the species. Ethological studies of female Bettas have revealed aggressive interactions that qualitatively parallel those between male Bettas. Given these similarities, four experiments were conducted with female Bettas to examine the generality of a widely reported finding with males: mirror-image reinforcement. Swimming through a ring was reinforced by a 10-s mirror presentation. As with males, ring swimming was acquired and maintained when mirror presentations were immediate (Experiments 1, 2, and 3) and delayed (Experiment 4). The failure of conventional extinction (Experiments 1 and 2) and response-independent mirror presentations (Experiment 3) to maintain responding confirmed the reinforcing properties of mirror presentation. These results extend previous findings of mirror images as reinforcers in males of the same species and illustrate a complementarity between behavioral ecology and the experimental analysis of behavior.     

Social overstimulation reduces subsequent aggression in Betta splendens

This paper examines the waning of intense aggressive behaviors in Siamese fighting fish subjected to continuous visual social stimulation. Damaging biting during subsequent fighting was dramatically reduced in fish which had been surrounded for several weeks by conspecifics, even though the overstimulated fish performed only opercular and fin displays to the fish surrounding them, not biting. The latency to opercular display was diminished, but the rate once opercular display began was not significantly different. In the 18 encounters observed, a socially overstimulated fish never dominated a control fish. This result suggests a visually mediated mechanism, which reduces biting tendency when there is prolonged, inescapable visual exposure to mildly aggression-releasing stimuli similar to those which trigger biting in live encounters. © 1994 Wiley-Liss, Inc.     

Sensitization of escape in female Betta splendens

Following 1 day of cohabitation with a male, female Siamese fighting fish showed heightened escape from male conspecifics (enclosed behind glass). Escape from males was general in that no particular male stimulus was required to provoke female escape. However, female conspecifics remained relatively attractive following exposure to a male. Tactile stimulation of females by males (biting, perhaps) plays some role and may be required in sensitizing females' escape from males. © 1996 Wiley-Liss, Inc.     

On the choice between eating and aggressive display in the Siamese fighting fish (Betta splendens)

In Expt 1, male Betta splendens were given a choice between food and a mirror image in a T-maze. All fish consistently preferred food. In Expt 2, the choice of fish that lived in the T-maze for the duration of the experiment was compared with the choice of fish that were transferred to the T-maze for each experimental session. Fish that lived in the T-maze consistently preferred food, but fish that were transferred showed a shift in preference toward mirror image. Differential inhibition of hunger and aggression by fear is suggested as the cause of the preference shift.     

Effect of various discriminative stimuli on choice behavior in male siamese fighting fish (Betta splendens)

The current experiment was an exploratory study empirically comparing three discrimination methodologies proposed for use in choice preparations with food rewards. Subjects were thirty-five, healthy, adult male Siamese fighting fish (Betta splendens). Subjects were randomly assigned to one of three discrimination groups: a Direction group (using left or right as discriminative stimuli), a Color group (using red or green as discriminative stimuli), and a Bubble group (using the presence or absence of air bubbles as discriminative stimuli). For all three discrimination groups, subjects chose between one or three food pellets in a submerged T-maze. The results from the experiment indicated a statistically significant preference for the three pellets of food over one pellet of food only for the Bubble group. Of particular note is the effect size and observed power obtained for the Bubble group, which was the only group which supported a reasonably powerful test for discrimination, given a sample size of 12 subjects and 0.94 effect size.     

Response acquisition by Siamese fighting fish (Betta splendens) with delayed visual reinforcement

Male Siamese fighting fish, Betta splendens, swam through a ring in an aquarium, breaking a photocell beam and initiating an unsignaled, resetting delay interval. Following delays of 0 s, 10 s, or 25 s, a 15-s mirror presentation released an aggressive display by the fish. Swimming through the ring increased in the absence of either a period of acclimatization to the reinforcer (analogous to magazine training when appetitive reinforcers are used) or explicit training of the response by the experimenters. Response rates were a decreasing function of delay duration. Other fish exposed to a schedule of response-independent mirror presentations failed to acquire and maintain the response. The results demonstrate the robustness and generality of the phenomenon of response acquisition with delayed reinforcement. They further qualify earlier observations about behavioral mechanisms involved in the phenomenon.     

Effects of mercury chloride (HgCl2) on Betta splendens aggressive display

Mercury chloride (HgCl2) is a toxic mercury salt and a major pollutant, that can be found in soil, water and air, with influences on behavior, physiology and adaptation to the environment. In this study two experiments were designed to examine interactions and effects of HgCl2 on some behavioral patterns of Siamese fighting fish (Betta splendens). In the first experiment we tested the effect of a progressive dose (five 0.04 mg) on aggressive display with exposure to a mirror, whereas in the second experiment we tested the effect of an acute dose (0.2 mg) on the aggressive display with exposure to a mirror. The experiments were performed on 5 consecutive sessions at intervals of 18 hours between sessions. Differences of performance were shown by subjects in the acute and progressive treatments when compared with a control treatment in the majority of behaviors evaluated, namely Floating, Slow Swimming, Wavy Swimming, Emerging, Bend, Square Move and Motor Display Components. Acute treatment was different from control only on Show Body, while the progressive group differed on Resting, Horizontal Display and Appropriate Display Components. Differences between Correlate Display Components and Total were also shown. Both the acute and progressive contamination with HgCl2 decrease the motor activity in the aggressive display, mirror-image test of Betta splendens, mainly on the progressive dose. This implies an impairment on feeding behavior, predator avoidance, reproductive behavior, mate choice and territoriality. These results suggest that in this fish species, the progressive dose has a greater effect on behavior in general and that both the acute and progressive contamination with mercury chloride affect many other aspects of behavior.     

Using visual reinforcement to establish stimulus control of responding of Siamese fighting fish (Betta splendens)

Stimulus control of ring swimming was studied with male Siamese fighting fish (Betta splendens) using 2-component multiple schedules in which the components were correlated with the presence or absence of air bubbles in the water. In Experiment 1, either response-independent mirror presentations or extinction was juxtaposed with immediate response-dependent mirror presentations. Rates of ring swimming generally were higher with immediate reinforcement than with either response-independent mirror presentations or extinction. In Experiment 2, different durations of response-dependent mirror presentations were juxtaposed. Generally, higher rates of ring swimming occurred with 15-s than with 0-, 1-, or 3-s durations. Results demonstrate that stimulus control of responding can be established with these fish under several conditions of differential reinforcement.     

Operant responding in Siamese fighting fish (Betta splendens) as a function of schedule of reinforcement and visual reinforcers

Siamese fighting fish were trained to emit an operant response that was reinforced by the opportunity to view a motion picture film image of another fish. Performance under various schedules of reinforcement was examined. When reinforcement followed every response and when reinforcement was delivered after every second response, the number of responses per session was higher than during operant level or during extinction. Reinforcement delivered following intervals of no responding (differential reinforcement of other behavior) markedly decreased responding. Light from a projector without film was found to be as effective a reinforcer as film reinforcement. Responding when projector light reinforcement followed every response was maintained at approximately the same level as that obtained under film reinforcement. Responses per session decreased when only the light was delivered on a differential-reinforcement-of-other-behavior schedule. The behavior of the fish during presentation of the film was markedly different from their behavior while the projector light was being presented.     

Effects of trophic poisoning with methylmercury on the appetitive elements of the agonistic sequence in fighting-fish (Betta splendens)

The aggressive display in Betta splendens is particularly prominent, and vital to its adaptation to the environment. Methylmercury is an organic variation of Hg that presents particularly pronounced neuro-behavioral effects. The present experiments aim to test the effect of acute and chronic poisoning with methylmercury on the display in Bettas. The animals were poisoned by trophic means in both experiments (16 ug/kg in acute poisoning; 16 ug/kg/day for chronic poisoning), and tested in agonistic pairs. The total frequency of the display was recorded, analyzing the topography of the agonistic response. The methylmercury seems to present a dose- and detoxification-dependent effect on these responses, with a more pronounced effect on motivity in acute poisoning and on emotionality in the chronic poisoning. It is possible that this effect could be mediated by alteration in the mono-amino-oxidase systems.     

Effects of imprinting and isolation on aggressive responses in chicks

The importance of isolation and imprinting as separate factors influencing early aggressive responses in chicks (Gallus gallus) was studied in two separate experiments. In addition the effect of the presence or absence of the imprinting stimulus in the test situation was examined in Experiment 1. Neither imprinting per se, nor the presence of the imprinting stimulus significantly affected aggressiveness. Rearing conditions (isolation vs social rearing) did, however, influence aggressive responses. Isolated chicks were significantly more aggressive than socially reared buds. The adaptedness of selective aggression in socially (naturally) reared chicks, as well as the indiscriminant aggressiveness caused by social deprivation is discussed.     

Preference for the sites of fighting in two teleost species

Males of two species of freshwater fish (convict cichlids and Italian freshwater gobies) fought with conspecifics and subsequently remained near the visual and spatial cues that had been paired with those social encounters. These data show that postfight preference for combat sites is a phenomenon of some generality among teleosts. The likely role of learning in establishing postfight preferences for the locales of aggression is discussed.     

Effects of fluprazine (DU 27716) upon aggressive and sexual behavior of testosterone-treated female rats

Female rats, chronically treated with Testosterone Propionate (TP), were injected with Fluprazine (DU 27716) or saline and tested for social aggression, masculine and feminine sexual behavior. Fluprazine-treated females were less aggressive than saline-treated females, as indicated by a shift from offensive to less offensive parameters of aggression. At the same time, mounting in Fluprazine-treated females was almost totally abolished, both in aggression tests and in tests for sexual behavior. Feminine sexual responses increased during aggressive encounters but were slightly inhibited when females were confronted with sexually active males. Females treated with Fluprazine and tested for mounting with a receptive female showed a substantial increase of offensive aggression directed at the receptive stimulus female. It is concluded that Fluprazine does not selectively inhibit offensive aggression in TP-treated female rats.     

Effects of selective breeding for high and low aggressiveness and of fighting experience on odor discrimination in mice

The present study was designed to determine whether male and female mice, selectively bred for high (TA) and low (TNA) aggressiveness, react in different ways when exposed to odors from males of the same strains. The effects of losing or winning fights on odor preferences in the TA males were also studied. The low aggressive TNA males were found to avoid areas soiled by the highly aggressive TA males. The TA males, on the other hand, were most interested in the areas soiled by other highly aggressive TA males. Along with decreasing aggressiveness, losing fights radically changed the odor preferences of the TA males, the soiled bedding from winner TA males now having a strong aversive effect. TNA females preferred the odors of TA males, while the TA females preferred the odors of TNA males. The genotype of the receiver of odor cues is important for the preference choices; this effect can, however, be changed through experience.     

The reinforcing properties of aggressive vs nonaggressive social interactions in isolated male ICR mice (Mus musculus)

Isolated male ICR mice in a T-maze consistently selected the goal box which enabled them to fight another mouse if the alternative goal box allowed no social interaction (Experiment 1). However, if the alternative choice enabled the isolated mice to interact with another mouse through a mesh screen which prevented fighting, the preference for the opportunity to fight did not appear (Experiment 2). Because the visual, olfactory, and auditory stimuli available through the screen appeared to be as attractive as the stimuli provided by the additional opportunity to fight, it is not necessary to conclude that the stimuli reinforcing the choice behavior in Experiment 1 were provided by fighting. Since there is no compelling reason to conclude that fighting is a primary reinforcer for these isolated mice, it is not necessary to argue that the high incidence of isolation-induced fighting is the reflection of a primary aggressive motive.