Weird Cory

So I have 3 corydora juliI in my 10 gallon tank with plants and sand. (I'm planning to get a 29 gallon with more cories). One of them is pretty particular compared to the others. It's pretty small compared to the others and it's got a lot of problems with it since I got it. Its gills doesn't move as much like the others (it looks like it's not breathing at all) and it goes up for air a lot. It doesn't eat much and it seems pretty lethargic most of the time. It still acts like this when the tank is cycled and all the other cories seem fine. Is this just a bad luck in genetics?

I'm surprised it's stayed alive for this long.

 

Got a pic ?

Must be breathing then hahaha

 

pic are helpful!

 

Here's the pics. The second one is to show what the other juliis look like.

 

I see two of them and I think they might be a sort of variation of the JuliI species.

 

Both C.trilineatus.

 

I agree but I don't see the "red gills".

 

How does it react on waterchanges ?

 

It reacts the same with whatever I do. I don't think it matters anymore now since it looks like it's about to kick the bucket