Which of the following secretes melatonin?

Correct option is C

Correct Answer: (c) Pineal gland
Explanation:
→ The pineal gland is responsible for secreting melatonin, the hormone that regulates circadian rhythms in fishes.
→ Melatonin secretion increases in darkness and decreases in light, helping maintain biological timing.
→ It influences locomotion, feeding, and reproductive cycles.
Information Booster:
→ Pineal gland is light-sensitive in many fishes.
→ Plays a role in seasonal breeding.
→ Acts as both an endocrine and photoreceptive organ.
Additional Information (Other Options):
(a) Thyroid: Produces T3/T4.
(b) Urophysis: Releases urotensins.
(d) Corpuscles of Stannous: Secrete Stanniocalcin.