Social experience impacts a variety of behaviors in fish as individuals learn from and are influenced by the actions of conspecifics. While isolation is often thought to be stressful for social animals, several studies have found that social isolation can reduce stress, anxiety-related behaviors and aggression. Additionally, developmental environment may not only influence the behavior of the individual, but also that of its offspring. Studies surrounding the influence of social context on the epigenetic factors of behavior in fish are increasing, but little is known on how parental social experience affects nutrition-related behavior in the subsequent generation.
The objective of this study was to investigate the effects of parental social experience (social housing or chronic isolation) on offspring feeding behavior, growth performance, and intestinal health when fed traditional and alternative diets. Zebrafish Danio rerio was used as a model species. At 21 days-post-fertilization (dpf), offspring from zebrafish raised in either chronic isolation (CIO) or in social housing (SHO) were randomly assigned to 3.0 L tanks with 25 fish per tank. Each tank was randomly selected to be fed either a fishmeal-based (FM) or soybean meal-based (SBM) diet. There were four treatment groups: SHO fish fed a FM (SHOF), SHO fish fed a SBM (SHOS), CIO fish fed a FM (CIOF), and CIO fish fed a SBM (CIOS). There were three replicates for each of the four treatment groups with a total of 12 tanks.
CIO fish had significantly higher initial weights at the beginning (21 dpf) and at the end of the experiment (53 dpf), the CIO offspring grew significantly more than the SHO fish regardless of diet type (Figure).
However, the SHO fish consumed more as a percent of biomass during the feed intake tests when compared to the CIO fish of the same diet type. Although not significant, fish fed with a SBM-based diet tended to have higher numerical expression of inflammation-related genes in the gut in both offspring treatment groups possibly suggesting some inflammatory response to the diet.
This study found that offspring that come from broodstock raised in isolation during development have significantly improved growth performance. Increasing feed intake by altering the social environment may be a useful tactic in selecting for brood-stock that produce similarly efficient offspring.