This study aimed to investigate the links between parasites and behavioural traits of juvenile Murray cod (Maccullochella peelii). The Murray cod is an endangered Australian freshwater fish for which restocking programs are in place and there is a growing human consumption market. However, little is known about the parasites of these fish and how these parasites influence their behaviour and survival. Fingerlings and yearling fish were sourced from a hatchery and the wild, and after acclimatisation in the laboratory, variation in behavioural traits was examined using emergence, exploration and predator inspection tests. The fish were then euthanised to determine their age and examined for infection with parasites. Wild fish had more camallanid nematodes and lernaeid copepods than hatchery fish. An information theoretic approach using Akaike’s Information Criterion (AIC) indicated that infection with protozoan cysts was an important factor for predicting the latency to emerge and explore a new environment, which was interpreted as reduced “boldness”. In contrast, the presence of lernaeid copepods was included in two of the four best models predicting predator inspection, indicating that infected fish were less likely to inspect a predator. Source of fish (wild or hatchery) was found to be a strong influence on behavioural responses in all our tests. All parasites found in the present study are known to result in clinical signs of diseases in their fish hosts, raising the possibility that responses in tests of behavioural traits reflect side effects of infection. Additionally, the effect of host adaptation to not show signs of parasite infection, or more simply that the effects on behaviour are subtle and difficult to reveal with small sample sizes, is discussed. Nonetheless, we propose that it is important that infection with parasites is considered in fish behavioural studies both to assess survival behaviour and to avoid misinterpretation of behavioural tests of animal personality.

这项研究旨在调查幼虫墨累鳕鱼（Maccullochellapeii）的寄生虫与行为特征之间的联系。）。墨累鳕鱼是濒临灭绝的澳大利亚淡水鱼，已经实施了放养计划，并且人类消费市场不断增长。然而，人们对这些鱼的寄生虫以及这些寄生虫如何影响其行为和生存知之甚少。鱼种和一岁鱼均来自孵化场和野外，经过实验室适应后，使用出苗，探索和捕食者检查测试来检查行为特征的变化。然后对鱼实施安乐死以确定其年龄，并检查其是否被寄生虫感染。与孵化场鱼类相比，野生鱼类具有更多的羽扇豆线虫和类足co。使用Akaike的信息标准（AIC）的信息理论方法表明，原生动物囊肿的感染是预测出现和探索新环境潜伏期的重要因素，这被解释为减少了“大胆”。相反，在预测捕食者检查的四个最佳模型中，有lernaeid pe足类动物存在，这表明受感染的鱼类检查捕食者的可能性较小。在我们所有的测试中，都发现鱼类（野生或孵化场）的来源对行为反应有很大影响。已知在本研究中发现的所有寄生虫都会在其鱼类寄主中导致疾病的临床症状，从而增加了行为特征测试中的反应反映出感染副作用的可能性。另外，讨论了宿主适应的影响，以不显示寄生虫感染的迹象，或更简单地讲，对行为的影响微妙且难以用小样本量揭示。尽管如此，我们建议在鱼类行为研究中考虑寄生虫感染对评估生存行为和避免对动物性格行为测试的误解都是很重要的。