Parental care, providing post-fertilization care to a developing brood, is beneficial for teleost fishes. Parental care is a challenging period for fish. Stress resulting from anthropogenic influences may make this already challenging period even more difficult, with the potential for negative fitness consequences. Experimentally elevating cortisol using intraperitoneal injections is effective in exploring the potential effects of the stress hormone cortisol on parental care. In Chapter 2, using a gradient of body sizes, I explore the interactive influence that elevated cortisol, body size, and brood size have on parental care behaviours and reproductive success in nesting smallmouth bass. In Chapter 3, using accelerometers attached to nesting smallmouth bass, I examine the influence of elevated cortisol on swimming behaviours and locomotor activity level, at a fine scale and over a longer time period. These results contribute to the growing body of literature illustrating the effects of elevated cortisol on teleost reproduction.