red spot on tail, trouble swimming, lethargic guppy. Is he a gonner?

[CT_]

So I have aguppy with a red spot on his tail and he's having trouble swimming---moving his body back and fourth instead of kicking he tail like the others.  I don't think its the shimmies and he's also got a red dot on his tail that I don't know if its bad or not.  It's hard to photograph but here's my best shot.

 

During feeding time and he came out but wasn't strong enough to get any food.  Right now, he's laying on his belly in the bottom under some plants gasping. 

Everyone else in the tank (7 cardinals and 2 guppies are happy)

TDS is 150, which is pretty typical for my tank, maybe even on the high side, which is why I don't think its the shimmies since he would have done it in the past 7 months if that was the case.

Edited October 25, 2021 by CT_

[Colu]

With the symptoms your describing I would treat for a bacterial infection with kanaplex or maracyn2. As he very lethargic he could be putting most of his energy into fighting an infection

 

Edited October 25, 2021 by Colu

[CT_]

Looks like I was too late.  I found him this morning under some hardscape.  😢

When I took him out I didn't see the red spot and he looked pretty normal (other than dead).