Table 1.
Key results of studies relating to social enrichment for laboratory zebrafish. Studies have been included where they have either addressed a preference (such as might be used to identify conditions which might promote welfare), or tested the effects of a condition intended to provide enrichment. Unless otherwise specified, all results here relate to the presence of the enrichment condition noted in the table compared with an absence of that condition.
| Study | Enrichment | Indicator(s) | Effect(s) |
|---|---|---|---|
| [45] | Presence of other zebrafish | Time spent near stimulus shoal | ↑ |
| [46] | Presence of other zebrafish | Distance between members of experimental shoal when mixed wth stimulus shoal (higher distances indicate greater mixing of experimental and stimulus shoals and therefore stronger preference) | ↑ |
| [47] | Presence of other zebrafish | Entries to compartment near stimulus shoal | ↑ for fish previously housed in groups or singly in barren tanks. No effect for experimental fish housed singly with an artificial plant. |
| Time spent in compartment near stimulus shoal | ↑ for fish previously housed in groups or singly in barren tanks. No effect for experimental fish housed singly with an artificial plant. | ||
| [48] | Presence of other zebrafish | Proportion of scan samples in which fish were near to stimulus fish or stimulus shoal | ↑ |
| [49] | Choice between shoals | Time spent near larger shoal | ↑ |
| [50] | Choice between shoals | Time spent near stimulus shoal | Males: preferred females over males, no preference between a mixed shoal and either a male or female shoal. No preference relating to shoal size. Females: no preferences relating to shoal composition. Preferred larger shoals over smaller shoals. |
| [51] | Choice between shoals | Time spent near stimulus shoal | Males: preferred groups of 3 males over single males; preferred single females to groups of 3 females. Females: preferred larger shoals regardless of the sex. |
| [53] | Presence of other zebrafish | Cortisol | ↓ |
| [54] | Presence of other zebrafish | Cortisol | ↓ in grouped compared with paired zebrafish No effect between grouped and individual zebrafish |
| Anxiety | ↓ | ||
| Rate of recovery of normal behaviour after stressor | ↑ | ||
| [55] | Presence of other zebrafish | Anxiety | ↓ |
| [56] | Presence of other zebrafish | Anxiety | ↑ |
| Serotonin | ↑ | ||
| 5HIAA | No effect | ||
| Dopamine | No effect | ||
| DOPAC | No effect | ||
| [57] | Presence of other zebrafish (exposure to stimulus shoal after isolation) | Cortisol | ↑ |
| Anxiety | No effect | ||
| Serotonin | ↑ | ||
| 5HIAA | ↓ | ||
| Dopamine | ↓ | ||
| DOPAC | ↓ | ||
| [58] | Presence of other zebrafish | Anxiety | ↑ |
| Cortisol | ↑ | ||
| [59] | Presence of other zebrafish | Cortisol (resting) | No effect |
| Cortisol (after chasing with a net) | ↑ | ||
| Cortisol (after predator exposure) | ↓ | ||
| [60] | Presence of other zebrafish | Cortisol (resting) | No effect |
| Cortisol (after chasing with a net) | ↑ | ||
| [61] | Presence of other zebrafish | Cortisol (in fish raised in isolation) | No effect |
| Cortisol (in group-raised fish after isolation) | ↓ | ||
| Neurogenesis | ↑ | ||
| [62] | Presence of other zebrafish | Latency to feed | ↓ |
| Neophobia | ↓ | ||
| [63] | Presence of other zebrafish | Cortisol (after chasing with a net) | ↑ |
| Cortisol (after being moved to novel tank) | ↑ | ||
| [71] | Housing in sexually segregated groups (as opposed to mixed-sex groups) | Fecundity | ↑ |
| Egg viability | ↑ | ||
| [72] | Housing in sexually segregated groups (as opposed to mixed-sex groups) | Weight | ↑ |
| Cortisol | ↓ | ||
| Inhibitory avoidance | ↑ | ||
| Activity in open tank test | No effect |
↑ = increase; ↓ = decrease.