Reyes-Mero Byron Manuel, Cruz-Quintana Yanis, Rodríguez-Canul Rossanna, Gisbert Enric, Santana-Piñeros Ana María
Grupo de Investigación en Sanidad Acuícola, Inocuidad y Salud Ambiental (SAISA), Departamento de Acuicultura, Pesca y Recursos Naturales Renovables, Facultad de Acuicultura y Ciencias del Mar, Universidad Técnica de Manabí, Bahía de Caráquez 130104, Ecuador.
Unidad Merida, Departamento de Recursos del Mar, Centro de Investigación y de Estudios Avanzados del IPN, Km 6 Carretera Antigua a Progreso, Mérida 97310, Yucatán, Mexico.
Animals (Basel). 2024 Oct 20;14(20):3037. doi: 10.3390/ani14203037.
Trichodinidae, a prevalent group of protozoan ectoparasites in aquaculture, cause rapid mortality in fish hatcheries. Despite their significance, knowledge about these parasites in farmed fish in South America, especially in native species that are currently being domesticated for aquaculture, remains limited. This study morphologically characterized the Trichodinid species that are infecting Pacific fat sleeper () larvae and evaluated their impact on larval rearing. Four pairs of broodstock were induced with GnRHA implants and placed in tanks containing 200 L of freshwater, with a water temperature of 28 ± 1.0 °C and a dissolved oxygen level of 4.00 ± 1.23 mg L, with partial water exchanges being performed daily. The larvae hatched 7 to 8 h after fertilization and were transferred to tanks containing water with the same quality parameters. Twelve hours post-hatching, the presence of was observed. Every 24 h, 60 larvae per tank ( = 180 per treatment) were sedated, and larval wet mounts were prepared, air-dried at room temperature, and impregnated with silver nitrate. Infection parameters and daily mortality were calculated. was observed to parasitize the pelvic fins, caudal fins, and heads of fish larvae, which showed lethargy and erratic swimming movements. The species showed a daily increase in the infection parameters, and a 58% rate of larval mortality was observed at the fourth day post-hatching (dph) in the infected tanks. In captivity, larvae typically survive up to 7 days post-hatching (dph) before reaching their point of no return due to the lack of adequate diet and feeding regimes. However, our study indicates that infestation accelerates mortality, causing infected larvae to die more quickly than uninfected ones.
三代虫科是水产养殖中常见的原生动物外寄生虫类群，可导致鱼类孵化场的鱼快速死亡。尽管它们很重要，但关于南美洲养殖鱼类中的这些寄生虫的知识，尤其是目前正在驯化用于水产养殖的本地物种中的寄生虫知识，仍然有限。本研究对感染太平洋睡鲇（）幼体的三代虫物种进行了形态学特征描述，并评估了它们对幼体培育的影响。用促性腺激素释放激素类似物（GnRHA）植入物诱导四对亲鱼，并将它们放入装有200升淡水的水箱中，水温为28±1.0°C，溶解氧水平为4.00±1.23毫克/升，每天进行部分换水。幼体在受精后7至8小时孵化，并转移到装有相同水质参数的水的水箱中。孵化后12小时，观察到有。每24小时，将每个水箱中的60尾幼体（每个处理180尾）麻醉，制作幼体水浸片，在室温下风干，并用硝酸银浸染。计算感染参数和每日死亡率。观察到寄生在鱼幼体的腹鳍、尾鳍和头部，幼体表现出嗜睡和游动异常。该三代虫物种的感染参数每日增加，在感染水箱中，孵化后第四天（dph）观察到幼体死亡率为58%。在圈养条件下，幼体通常在孵化后（dph）存活长达7天，然后由于缺乏足够的食物和喂养方式而达到无法挽回的地步。然而，我们的研究表明，感染会加速死亡，导致受感染的幼体比未受感染的幼体死亡更快。
