Figure 7. Surface fish and cavefish show a differential plasma cortisol response to confinement.

Cortisol levels in surface fish (A) and Pachón cavefish (B) raised in confined (5/10 ml; left bar for each day) or unconfined (40 ml; right bar for each day) conditions for 35 days. Errors bars represent standard error of the mean. Asterisks indicate statistically significant cortisol levels. See Table 2 for further information, basal cortisol values for controls raised in 100 volumes, and statistical analyses.