Five Betta splendens were exposed to a mirror for ten days. The mirror was then removed for a recovery period, replaced for 48 hours, removed for a second recovery period, and so on in such a manner that each fish was given recovery periods of 15 minutes, 6 hours, 24 hours, 48 hours and 4 days in an order counterbalanced across subj ects. In most subjects the threat display increased during the first few minutes of mirror exposure (Fig. I). It decreased rapidly during the first 24 hours and then more slowly to a level which was low but above zero (Fig. 2). The recovery data indicate gradual recovery over the first 1-2 days after removal of the mirror; further recovery was either non-existent or very slow, and no subject showed a full return to the initial level.