Third eye of a fish - Pineal gland
 

The third eye of a fish - Pineal Gland

If you think the turn on timing of the tank light is not crucial, then read these and think again.

Fish and Amphibians

The pineal gland of fish and amphibians is located near the skin and functions to detect light.

http://faculty.clintoncc.suny.edu/fa...m/endocrin.htm

Pineal Gland

The pineal gland is a light sensitive neuroendocrine structure that lies in the anterior brain and is a well-vascularized organ. This gland secretes melatonin that may play a role in controlling reproduction, growth, and migration.

There are cells with photopigments in the pineal gland of the brain, which seem to regulate daily rhythms and hormone release. But rods and cones were thought to be the only photoreceptors in the vertebrate eye.

http://www.afip.org/vetpath/POLA/POLA96/fish.txt

http://www.nature.com/news/1998/9807...0709-4_pf.html

Fish Pigment Keeps Body Clock Ticking

The researchers suggested this could have some effect on the creature's body clock, much like the effect of visible light on higher animals' pineal gland.

In many animals, light intensity affects nerve activity in the pineal gland, which is responsible for secreting hormones such as serotonin and melatonin. These hormones influence the animal's circadian rhythm, the cycle of activity and rest.

http://www.flmnh.ufl.edu/fish/InNews...gment2004.html

HMMM.. maybe this explains why many of our fish dont breed in captivty..?

location of the third eye

in this case - a visible pale white spot

Location of the pineal gland (the third eye)

light ray will affect their behaviour such as feeding, breeding.. etc.

In some habitat, there are seasons, cold & heat and long day short nite etc.

All these will stimulate them as what you may read.