Table 1. Total occurrence of unusual behaviours shown by seven fish during 20-min observation periods during the first 5 d after presentation of the mirror.

Individual fish	Occurrence of behaviour a	Occurrence of behaviour b	Occurrence of behaviour c	Occurrence of behaviour d	Occurrence of behaviour e	Total occurrence of behaviours
#1	2	0	4	39	0	45
#2	0	0	30	0	0	30
#3	54	0	0	0	0	54
#7	15	0	0	0	35	50
#13	33	0	0	0	0	33
#20	31	17	2	0	2	52
#21	2	0	2	0	6	10
Total	137	17	38	39	43	274

Number of atypical behaviours shown by seven fish (individuals #1, #2, #3, #7, #13, #20, and #21) for each 20-min observation period in the first 5 d after presenting the mirror: (a) dashing along the mirror, (b) dashing with head in contact with the mirror, (c) dashing and stopping, (d) upside-down approach, and (e) quick ‘dance’. The most frequent mirror-testing behaviour of each fish is in bold. Descriptions of behaviour are as follows. Dashing along the mirror: rapid dashing along the mirror surface in a single direction for 10–30 cm. Fish do not swim directly against or make contact with their mirror reflection. Dashing along the mirror with the head in contact with the mirror: the head of the fish was always in contact with the mirror during dashing. Dashing and stopping: fish rapidly dashed towards the mirror reflection but stopped before contact with the mirror. Upside-down approach: fish swim in an upside-down posture while approaching the mirror. Quick ‘dance’: fish spread all of their fins and quickly arched and quivered the body several times over ca. 1 s at a distance 5–10 cm from the mirror; no dashing to the mirror is observed.