Mollies back fin not working

[clusby171]

Afternoon all.

We have a black Mollie (unsure if it’s a male or female), but the last couple of days we have noticed it isn’t able to swim properly.

It goes almost vertical, and it’s back tail doesn’t seem to be working anymore.

Parameters are fine.

All the other mollies are fine also.

Thanks

 

[WaterGardener]

What are the numbers for the water parameters?

How old is the fish? Have you added anything new to the tank recently?

Looks like a male to me.

 

[Mmathis]

Hello and welcome! Ditto what @WaterGardener asked, including tank size.

 

[j.w]

@clusby171