HELP!!!GOLD DOJO LOACH!!!

[Columbian Shark Catfish]

Over the past couple of weeks I've noticed this brown spot growing on my golden weather/dojo loach. It doesn't grow outwards, but it spreads.
He hasn't been acting strange; he eats normal, swims like he always has, but i just wanted to know what it is :S

I do a 35-60% water change every week. Tankmates are: 2 Zebra loaches, 1 bumblebee catfish, 1 clown plecostomus.

Pics:

 

[Columbian Shark Catfish]

TTT

 

[Lupin]

Looks like part of its color if you ask me.

 

[wingate2581]

Looks like part of its color if you ask me.

+1 My friend has one and the spot grew with the fish. Nothing wrong with hers.

 

[k0y0te]

i am not to sure what that spot is. i have had a dojo for several years. i think it might be just part of the coloring of him but dont quote me on it.

 

[Columbian Shark Catfish]

Looks like part of its color if you ask me.

Oh, that's what I told my Mom. But I just wanted to make sure. Thanks

 

[metalyx]

I had the same thing pop up on one of mine. Had him for just over a year and he grew from 3" to about 11". At month 6 his face started to develop a brown spot very similar. You will see this much more in the chain stores but attached is a pic and don't worry.