Effect of feeding frequency and water salinization on early development of Pyrrhulina brevis, an Amazonian ornamental fish

ABSTRACT Pyrrhulina brevis is an endemic fish from the Amazon basin that is valued in the ornamental fish market. In larviculture, fish are very sensitive to stressors and have a high mortality rate. Salinized water may provide more energy to overcome stress and feeding frequency is an important strategy to improve productive performance. Therefore, the aim of this study was to evaluate the best feeding frequency and the best level of water salinization for larval development of P. brevis. A total of 360 post-larvae of P. brevis (5.26 ± 1.65 mg, 5.57 ± 0.68 mm) were randomly distributed in 36 aquariums (1 L) in a 3x4 factorial scheme, to evaluate three concentrations of salt in water (0, 1 and 2 g L-1) and four feeding frequencies (once, twice, three and four times a day). We offered 150 Artemia nauplii per day and per post-larvae during 15 days. The fish kept at 1 g L-1 salinized water, and those fed 3 and 4 times a day presented significantly greater final length and weight, weight gain, and specific growth rate for length and weight. An interaction between salinized water and feeding frequency was observed for survival rate. We conclude that, during the initial rearing phase of P. brevis, feeding frequency of three times a day and salinized water at 1 g L-1 is recommended.

摘要
短体盔脂鲤（Pyrrhulina brevis）是亚马逊流域特有鱼类，在观赏鱼市场具有较高经济价值。在鱼类育苗过程中，幼体对胁迫因子极为敏感，且死亡率居高不下。咸化水体可为幼体提供更多抵御胁迫的能量，而投喂频率则是提升生产性能的重要调控策略。因此，本研究旨在探究最适宜短体盔脂鲤幼体发育的投喂频率与水体咸化水平。
本研究共选取360尾短体盔脂鲤后期幼体（体重5.26±1.65 mg，体长5.57±0.68 mm），采用3×4因子试验设计，将其随机分配至36个1升水族箱中，设置3组水体盐浓度（0、1、2 g·L⁻¹）与4组投喂频率（每日1次、2次、3次、4次）。实验周期为15天，每日为每尾幼体投喂150个卤虫无节幼体（Artemia nauplii）。
结果显示，饲养于1 g·L⁻¹咸化水体中，且每日投喂3次或4次的幼体，其最终体长、体重、体重增重率以及体长与体重的特定生长率均显著优于其他组别。此外，水体咸化水平与投喂频率对幼体存活率存在显著交互效应。
综上，在短体盔脂鲤的初期育苗阶段，推荐采用每日投喂3次、水体盐浓度为1 g·L⁻¹的养殖方案。