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When viewing the petricolas the other night (in darkened tank and room) I noticed a white "spot" on their heads which stood out visually from the rest of the body. It is not apparent or readily apparent anyway during the daytime or in the lighted tank nor does it show in the dark but just is apparent when I viewed with a flashlight. It is small, about the size of the smaller dots in its coloration. I usually don't view the catfish this way but just happened to want to check a noise and when looking through the tank noticed this mark which appeared as one would swim in the direction of where the light came from. Does anyone know what this is?...besides an hallucination : )

It occurred to me that it might be some sort of sensory device since they move around in the dark but that is just a guess. I have not seen this on the s. eupterus that I have but maybe it IS there and I just have not noticed.

The lightened spot you see is probably where the pineal gland is. Commonly referred to as a "third eye", this is a light sensitive organ (part of the midbrain) that is important in helping the animal regulate diurnal (day/night) cycles.
I've often noted the lightened spot (pineal gland) showing up in catfishes at night. Many of the bagrids I have kept (<i>Leiocassis</i>, <i>Pseudomystus</i> and <i>Bagrichthys</i>) often also have this pale spot on their foreheads at night.

I came to the right place! Now I will have to check out the eupterus more closely to see if it also has this spot!

Hmmm... I learned something too! I often watch my catfish at night, but never noticed that before. Thanks, Heok Hee!

Dinyar