Studies on character and sociality of fishes using self-feeding mathod.

“自食性”是研究鱼类群体社会性的有效工具。这就是说，水箱中自动投食系统的开关位置被鱼类认为是一个很好的诱饵场所，个体之间必须发生竞争才能占据这个好的位置。在这种竞争的情况下，社会等级可能建立在一个鱼群内，这一复杂的过程有可能用自食法来分析。本实验利用鱼类个体在自食性条件下的开关激活频率和摄食频率来分析蓝鳍太阳鱼和金鱼的社会优势度，用摄像机记录背鳍底部植入可区分颜色标记的两个个体的自食行为，观察哪条鱼是否启动了开关，哪条鱼是否摄食了所投放的食物。两套竞赛实验是…同时建立更多的个体，如果在实验结束时观察到排名，那么就建立了一个新的实验组，使用以前实验坦克中的优势个体的组合。同时，还建立了一个新的实验组，使用了从属个体的组合。再重复2次竞争实验，观察它们的自食行为。在竞争实验中，两种鱼都观察到了关注开关激活的个体和不关注的个体。这可能是由于每个人的学习能力不同造成的。两个个体之间的开关激活频率的差异随着实验时间的推移而变得越来越大，这可能是由于在自食行为中通过重复开关激活来重新学习所致。然而，在摄食频率方面，两种鱼之间观察到了很大的差异。在金鱼中，即使是没有操作开关的下级也能吃下鱼丸，体重增加。反之，在优势鱼的抑制下，蓝鳍金枪鱼的子代不能摄取颗粒，体重下降。因此，在蓝鳍金枪鱼中，自食性学习能力的差异及其攻击性气质互补地促进了鱼类群体中较强的社会等级的产生。在金鱼中，虽然自食性DO的学习能力存在差异，但表明该物种可能不存在社会等级。较少

"Self-feeding" is an effective tool for studying the sociality of fish group. That is to say, the place of switch of self-feeding system in a tank is recognized as a good baiting field by fish and a competition must occur for occupying this nice place between individuals. Under such a competitive circumstance, the social hierarchy may be established within a fish group and there is a possibility that this complex process can be analyzed using self-feeding method. In this experiment, we analyze the social dominance of bluegill sunfish Lepomis macrochirus and goldfish Carassius auratus using both switch activating frequency and food in take frequency of fish individuals under self-feeding condition.Self-feeding behavior of two individuals with distinguishable colored markers implanted at the basal part of dorsal fin was recorded with video camera and whether which fish activated the switch and whether which fish took the delivered food was observed. Two sets of competition experiment wer … More e established simultaneously, and if the rank is observed at the end of the experiments, then a new experimental group was established using a combination of dominant individuals from the former experimental tanks. At the meantime, a new experimental group using a combination of subordinate individuals was also established. And then, 2 competition experiments were repeated again and their self-feeding behavior was observed.In the competition experiment, individual concerning the switch activation and the individual that is not concerned were observed in both fish species. This may be due to the difference in the learning ability of each individual. The discrepancy of switch activation frequency between two individuals became larger and larger by the time courses of the experiments, and this may be due to the re-enforcement of learning by the repetition of the switch activation in self-feeding behavior. Concerning the food intake frequency, however, large difference was observed between two fish species. In goldfish, even the subordinate that did not operate the switch was able to take pellet, and the body weight increased. On the contrary, the subordinate in bluegill could not take pellet by the suppression by dominant fish, and the body weight of the subordinate decreased. Therefore, in the bluegill, the difference in the learning ability for the self-feeding and its aggressive temperament complementarily promoted the production of the strong social hierarchy in the fish group. In the goldfish, it is indicated that the social hierarchy may not exist in this species, though the difference of the learning ability for the self-feeding do exists. Less