All types of animals, including humans, have specific attributes that are used to compete for basic biological needs such as food, mates and habitat. A variety of species, ranging from aphids to squirrels and including our beloved betta, have thus evolved extraordinarily high aggressive behaviors to defend their territories.
But how much is too much? And does the typical breeder keeping bettas in captivity contribute to their heightened aggression?
An animal that is overly aggressive does not typically survive long in nature. There is considerable physical cost in super-aggression (i.e., time and energy) that would outweigh the expected benefit; the increased risk of physical damage, an increased risk of predation, and lost opportunity that is afforded to other animals whose energy is directed to foraging and mating behaviors. In the case of bettas in the wild, the cost grows larger as the bettas continue to fight longer, so they must stop the fight at a pivotal point where the expected benefit would balance the accompanying cost of the fight. If the bettas stopped too early, they would not gain the benefits of food, mates, and habitat at all; on the other hand, if the animals continued to fight intil it was too late, the accompanying cost would override the benefit -- even if they won! So bettas in the wild know the appropriate time to stop fighting.
Several studies have shown that an early deprivation of social stimuli leads to maladaptive development of excessive aggression in a variety of animals, ranging from monkeys to crickets. In one study it was shown that rhesus monkeys reared with extraordinary social deprivation (no contact with mothers, other juveniles, or other animals) failed to develop truly normal sexual, play and aggressive behaviors. Instead, the unsocialized monkeys redirected their aggression toward themselves, so that a severe self-punishment occurred in response to the appearance of an intruder (something to think about when our typically isolated captive-raised male bettas tear their own fins off when they are allowed to interact with another betta!). In crickets, deprivation of physical contact has been found to cause an excessive aggression in terms of increased attacks, and also misdirected attacks to females.
In the wild, bettas are known to have a characteristic repertoire of agonistic/aggressive behaviors such as raising of the gill covers and spreading of the fins. The fights between males are violent and often involve physical damage, whereas females do not fight nearly as aggressively, suggesting a functional link between aggression and reproduction. Nesting males become more aggressive, and females choose mates according to the outcome of local competition between the males.
In an experiment performed by students at the Graduate School of Bioagricultural Sciences in Japan, we see an interesting link between lack of normal social interaction and aggressiveness in bettas.
The fry in this experiment were all from the same spawn and removed from their father on their first day of becoming free-swimming. Thereafter, the fry were raised together until 6 weeks of age and fed with live brine shrimp and frozen bloodworms. At 6 weeks, 110 unsexed individuals were chosen for the experiment and allocated into the following 4 groups with different rearing conditions.
In Group-I (highly social group), 5 fish were raised together in a small tank. In Group-II (highly social and isolate group), individual fish were given their own containers but allowed to view the activity in the social Group-I tank. In Group-III (social and isolate group), the fish were given their own tanks but allowed to view their individual siblings in their own tanks, typical of the "jarring" situations found in fishrooms today. In Group IV (non-social and isolate group), the fish were isolated in their own tanks and kept carded at all times. Other than their social differences, all fish were treated and fed exactly alike.
At 12 weeks old it became evident that the bettas in this experiment were a mix of males and females, and it was determined that the differences in rearing had no evident effect on the physical development and sexual maturation.
Observations into fighting behavior were conducted in a tank with a removeable solid partition and videotaped for posterity. In all but a few of the Group-I fish, fighting began as soon as the partition was removed. The bettas were allowed to spar until a clear winner was determined, or for a maximum of 2 hours. The majority of the cases ended with the retreat of the losing male, who then displayed his "submission" horizontal stripes. If a winner was not determined by the 2-hour mark, the contest was considered a "draw".
The following 3 types of agonistic behaviors were identified and counted in this study; butt-or-bite, chase, and gill cover erection.
Butt-or-Bite: A fish rapidly approaches another fish, then strongly butts or bites the opponent with his mouth. The mouth may or may not be open at the time of the physical contact. Butt-or-bite sometimes results in physical damage to the opponent's fins and scales.
Chase: A fish rapidly chases a fleeing opponent. This attack is not accompanied by any physical contact.
Gill cover erection: A fish widely erects the gill covers on boths ides and desplays toward the opponent. No physical contact accompany.
It is interesting to note that in the Group-IV Non social/isolate group, the males won in ALL of the fight sessions. In addition, the Group-IV males were much more prone to continue aggressive attacks on their opponent after the loser had already displayed submission.
It was suggested in this study that the inability of the Group-IV males to known when to stop fighting was directly related to the lack of early socialization. Interestingly enough, it was found that the males in the other groups, even though some of them had been isolated in their own tanks, were able to pick up on that important cue simply by interacting and observing the other bettas in their vicinity. These hyper-aggressive Group-IV males were not able to be rehabilitated, even after living for some time in a more social situation.
Another theory that was not expounded upon but holds merit is that the social interactions suppressed the aggressive behaviors in Groups I-III. It has long been observed that male bettas show a gradual waning of intense aggression when they were allowed continuous social interaction; it is for this reason that so many betta exhibitors "card" their bettas (cut off visual of any other betta) before a show. This causes the betta to deport better when it is finally allowed to see another betta while being judged.
I believe that the association of increased aggression and the widespread modern rearing techniques of bettas in captivity may have much to do with the high damage/mortality rate among breeding partners, and even the incidences of tail-biting, which can be likened to the self-mutilation described earlier in this article by the rhesus monkey raised under similar circumstances. Most betta breeders today isolate the males, and sometimes the females, at a relatively young age (4-8 weeks) in order to preserve finnage. In most cases these fish are then kept carded for most of the day and are unable to socially interact with other bettas in any way, shape or form. The breeder who uncards their bettas for a few hours of the day to "let them excercise" is then treated to a real display of wild flaring and aggression as these unsocialized bettas go into hyper-territorial mode. This is great for the hobbyist who appreciates beauty, or the exhibitor that requires their fish to display for the judge, or a seller who wishes to offer photos of their fish hyper-aggressively flared. But it may be a disservice to the breeder, who then has to deal with the inherent problems involved in trying to spawn an unsocialized betta; i.e. reluctance to build bubblenest, attack and murder of the female, and egg and/or fry eating. Many breeders raise their females together in a social environment until a much later age than the males, so these socialized females are ill-equipped to deal with the agonistic behavior of the unsocialized male partner. In some cases the females have been unsocialized as well, resulting in fighting and damage to both parties involved.
It has often been reported by breeders who practice "Natural fry-rearing" where the father is left with the fry long-term instead of removed when the fry are free-swimming, that the males and females raised in this situation tend to spawn faster, cause less damage on a whole, and the males are better parents (less prone to egg and fry eating or nest abandonment) than bettas that were raised without their father. However, the male WILL cull the fry down to a number that he feels is reasonable according to the amount of water he is provided. Breeders who are planning on allowing the male to raise the fry should plan on that spawn actually yielding approximately 2 fry per gallon of water.
I would be interested in hearing some feedback from some of the breeders out there who have raised their bettas in a more social environment, and from others who have completely unsocialized their fish. It is certainly worthy of note that the most successful fighting plakad trainers in Asia practice standard anti-socialization of their fighters from a very early age, and are "rewarded" with much more successful prizefighters. How do you raise YOUR bettas?
A Non-Social and Isolate Rearing Condition Induces an Irreversible Shift toward Continued Fightings in the Male Fighting Fish (Betta splendens), by Tamako Ishihashi, Yoko Ichikawa and Toshiya Matsushima - 2004, Zoological Society of Japan