Table 1.

Affiliative behaviour before and after exposure of N. pulcher to an acute stressor for individuals that recovered with their own social group in experiment 1 (n = 14). Values for an individual fish represent the average of three 5 min observation periods. Behaviours are reported as means ± s.e.m. Significant differences (p < 0.05) are indicated by italic font. Rates of affiliative behaviours following air exposure did not change across time when individuals recovered with their own social group (electronic supplementary material, table S4). Therefore, post-stressor values of affiliation for each focal fish were averaged across the three observation periods during recovery and were compared to pre-stressor values.

behaviour		pre-stressor	post-stressor	χ 2	p-value
affiliative acts	received	0.4 ± 0.2	0.1 ± 0.1	4.94	0.02
	performed	0.4 ± 0.2	0.2 ± 0.1	1.74	0.19
time near group members (s)		32.4 ± 5.8	23.2 ± 4.5	2.09	0.15