Fin rot on my cardinal tetras?

[abrage22]

I noticed a few days ago that all four of my card. tetras seem almost like part of their back fin is missing, like something has torn part of it off. Well tonight i'm noticing a couple of them are acting kinda strange, their twitching against the front of the tanks glass, I guess i don't how else to explain it
Anyways, I noticed one has some white on its tail fin.
My tanks a 28 gallon, been set up for 4 or 5 months now. All my water perameters are in check. I do a 15% water change every week. I have the 4 cards, 5 serpae tetras, 2 mollies and 3 cories. All the other fish seem to be happy and healthy.
If I can give any more info to help determine what or if theres a problem here, let me know.

 

[abrage22]

Anyone.........

 

[Aces11]

Ya it does look like some kind of fungus or bacterial infection. Melafix works really on repairing fins and treating things like that.

 

[abrage22]

Great, thanks for your help

 

[abrage22]

Ok so I stopped dosing the Melafix after 7 days on Saturday like the instructions said. It definetly helped, the fish are improving. So should I just let it stay in the tank, or should I do a big water change to remove most of it? The fish don't fully have all the tailfin back, but their almost there. Also, one of the cardinals appears to have a green stomach, and is constantly opening and closing its mouth, does this sound like it may be a problem?

 

[Aces11]

You can do a water change and refuse if you want. I haven't kept cardinals but a green stomach doesnt sound normal.

 

[abrage22]

Alright, so I did a normal small water change a few days ago and decided to just not dose anymore and see what happens. Of course, a couple fish are losing fin again, so I'm guessing just dose for another week? Putting more in that water with almost a weeks worth already in the tank won't hurt anything will it?

 

[Aces11]

No it's all natural. It shouldn't hurt As long as you do a water change before and after the second week of dosage.

 

[abrage22]

Great, thank you!