• Primary Endocrine Stress Response:
• In teleosts, acute stress triggers activation of the Hypothalamic-Pituitary-Interrenal (HPI) axis: hypothalamic CRH stimulates pituitary ACTH release, triggering the interrenal tissue to synthesize and secrete cortisol.
• Basal vs Stressed Titer:
• Basal resting levels in undisturbed teleosts: $\lt 5 - 10\text{ ng/ml}$.
• Following acute stress exposure (netting, crowding, confinement), plasma cortisol elevates rapidly, typically peaking within $30 - 120\text{ minutes}$ in the range of $30 - 300\text{ ng/ml}$ (commonly $50 - 200\text{ ng/ml}$ in salmonids, carps, and bass).
• nalysis:
• (30-300 ng/ml): Correct standard physiological acute range.

Correct option: (3) 30-300 ng/ml