Is there something wrong with my pygmy cory?

[Calamardo Tentaculos]

I noticed that one of my female cories is being a lot less active than the others. On closer look, it seems there are some white spots and green marks on it's body.


In comparison, here it is another cory for comparison. It is the one on the left.

Is it me or does it seem skinnier than the other cory?

 

[G H Nelson]

The fish on the left looks like a male!
They look okay to me.
Although I'm not a Corydoras expert!

 

[riioKen]

I noticed that one of my female cories is being a lot less active than the others. On closer look, it seems there are some white spots and green marks on it's body.
View attachment 213349

In comparison, here it is another cory for comparison. It is the one on the left. View attachment 213350

Is it me or does it seem skinnier than the other cory?

I have pygmy, I'm no way expert but they are very calm and school very tight together (in my tank). I think he's a male (I have some rounded and some skinnier) I have them since May, 0 death and 0 change in their shape. The white spot are present in mine too

 

[Calamardo Tentaculos]

The fish on the left looks like a male!
They look okay to me.
Although I'm not a Corydoras expert!

I have pygmy, I'm no way expert but they are very calm and school very tight together (in my tank). I think he's a male (I have some rounded and some skinnier) I have them since May, 0 death and 0 change in their shape. The white spot are present in mine too

Thanks for your comments.

@riioKen could you share more on your tank and how you care for them? I've been losing cories over the last month and would like to figure out what I did wrong

 

[riioKen]

Thanks for your comments.

@riioKen could you share more on your tank and how you care for them? I've been losing cories over the last month and would like to figure out what I did wrong

Nothing special, I have a 300 litres Dutch style (before I had a 80 litres tank, the cories come from there).
The tank livestock is formed by cpd, ember tetra, pygmy Cory, otos and amano.

23°
GH 6
KH 2

I don't feed directly the Cories, I feed very small pellets 0.5mm but I check that some pellets sink at the substrate level. 1 or 2 times x week I drop an algae wafers.

Their behavior is mixed, but they always go around in couples, often they all school tight together rarely they swim alone. I have them since May, I lost 1, 3 month ago, physically perfect day before "healthy" the day after upside down without any sign of attack or infection. I like them a lot