This study investigates the effect of an aquarium on pre-treatment anxiety, fear. frustration, and depression in electroconvulsive therapy (ECT) patients. Forty-two patients consecutively referred for ECT were rotated between rooms with and without aquariums. Self report measures of depression, anxiety, fear, and frustration were obtained, along with heart rate and blood pressure measurements. Preliminary mixed-model, repeated measures analysis of variance (ANOVA) revealed no significant differences between the aquarium and control conditions on any of the dependent measures. A trend toward significance was found for self reported anxiety (p=0.08) and further data were collected. Subsequent mixed model, repeated measures ANOVA confirmed the trend toward differences (p=0.08) in anxiety between the aquarium and control conditions. Factoring out demographic factors, the average patient experienced 12% less anxiety in the presence of an aquarium.