potamotrygon motoro with black spots

[angelos7577]

Hello all , i am keeping 5 potamotrygon motoro rays in 2.300 liters plywood tank , 3 males and 2 females , feeding them with frozen fish , prawn and mussel , 1-2 times per day , doing 20% water changes per week , water measurements are NH4 less than 0,05 , almost none , NO2 just a little , less than 0,3 and NO3 10 .
I got most of them for many months.I noticed that 1 male got long ago 2 small black spots on top of his disk and recently 1 female got 5 small black spots also on top of the disk and wonder what these spots are .All rays are active and eating all the time and don't have any other strange mark on them.
Does anyone know why these spots appeared , could this be due to water parameters or some kind of parasite or bacterium.....
Here are photos of these 2 rays .

 

[angelos7577]

In the red circles are the small black spots that i am telling you about.

 

[StingraySteve]

are your rays wild caught or captive bred? I've seen some captive bred 25% leo/motoro hybrids with black spots like that.

 

[saganeer]

do they move? could be fish lice. Closer pics would help

 

[aquaman45]

do they move? could be fish lice. Closer pics would help

Looks like Argulus to me also.......better pics are needed.

 

[angelos7577]

Hope these photos can help you more.

 

[aquaman45]

Just looks like pigment...nothing to worry about.

 

[angelos7577]

I don't think that is argulus , no irritation at all at these spots on the rays.
They look like pigment spots , exactly.Very strange , maybe it's their color pattern , not sure , just seems odd as now they are more visible and dark.

 

[angelos7577]

Hello all , here are some better and closer photos of the black spots on the female potamotrygon motoro.
Touched them , didn't feel something , just the ray's skin and got no irritation there at all.
It also got 1 spot like these under its disk , got no clue what they are ....
The ray is moving and eating well , as usual.

 

[aquaman45]

Just random pigment dots Angelo, I suggest you forget about them and carry on enjoying your rays, they look nice healthy fish.

All the best to you!