Fish Meal Replacement and Early Mild Stress Improve Stress Responsiveness and Survival of Fish after Acute Stress

Abstract

Stress responsiveness and fish meal (FM) replacement are two of the most important concerns toward achieving sustainable aquaculture. The purpose of this study was to see how early mild stress (netting) and FM replacement with meat and bone meal (MBM) affected oscar (Astronotus ocellatus; 5.2 ± 0.9 g) growth, hematology, blood biochemistry, immune responses, antioxidant system, liver enzymes, and stress responses. Oscars were subjected to a 3 × 3 experimental design (three fish meal replacement levels: 250, 180 and 110 g/kg of FM in diets; three stress periods: 0-, 2- and 3-times early mild stress). After ten weeks of the experiment, FM levels in diets did not affect growth data, but the survival rate after the acute confinement (AC) stress was lower in 11FM treatments (47.7% compared to 67.7%) than others. Fish exposed to the 3Stress schedule had a lower growth (31.03 ± 6.50 g) and survival rate (55.5%) after the AC stress than the 2Stress group (38.92 ± 6.82 g and 70.0%). Lower survival and growth rate in the 3Stress and 11FM groups coincided with the lowest blood performance, total protein, lysozyme, complement C4, complement C3, immunoglobulin, superoxide dismutase, catalase, glutathione peroxidase, and the highest glucose, cortisol, low-density lipoprotein and aspartate aminotransferase serum levels. Altogether, this study revealed that it is possible to replace FM with MBM up to 28% (180 g/kg of FM) without negative effects on the growth and health of juvenile oscar as dietary 110 g/kg of FM impaired fish health. While fish welfare should be considered, we can conclude that mild stress (2Stress) during the farming period, but without adding excessive alternative protein sources, can improve the stress responsiveness of oscar.

Enzymatic Stress Responses of Coreius guichenoti to Microplastics with Different Particle Sizes

“…To our knowledge, this study is the first to investigate the connections between the stress responses and microplastics in C. guichenoti . The selected enzymes in this study are commonly recognized as indicators of stress [ 54 , 55 , 56 , 57 , 58 ], effectively demonstrating the stress response of C. guichenoti after being exposed to microplastics.…”

The Recovery Time between Early Mild Stress and Final Acute Stress Affects Survival Rate, Immunity, Health, and Physiology of Oscar (Astronotus ocellatus)

“…This study was a follow-up study from our EMS project. After doing three studies [4,13,14], we understood that stress at two out of ten weeks did not impair growth, stress response, and most of the measured parameters, but it did improve the survival rate after AC stress. However, it raises the question of whether stressed fish in weeks 2 and 4 would respond differently than those exposed to stress in weeks 7 and 8.…”

“…The optimum protein, lipid, and fish meal levels and their interaction with EMS have been tested before [4,13,14]. Therefore, an optimum isonitrogenous (450 crude protein/kg feed and 180 g/kg fish meal) and isolipidic (180 g/kg lipid) were used for this study.…”

“…However, studies that tested the effect of early mild stress (EMS) or eustress in aquatic species are limited to our previous studies [4], and other fish studies that lower hypothalamic and brainstem serotonergic responses to stress and cortisol responsiveness were observed [10][11][12]. In our earlier studies, the interaction of EMS with different levels of lipid [4], protein [13], and fish meal replacement [14] were investigated. The highest survival rate after final acute stress (confinement stress) was observed in oscar exposed to two weeks of EMS out of a ten-week trial [4,13].…”

Fish Responses to Alternative Feeding Ingredients under Abiotic Chronic Stress

“…The work with positive results in fish related to stressful conditions and the partial substitution of FM with MBM occurs under acute stress. Zare et al (2023) recorded netting results as a stressor and FM replacement with MBM and their interactions on growth, blood chemistry, immune responses, antioxidant system, and stress response in the ornamental fish Astronotus ocellatus [87].…”