Fin rot

[Spencer1044]

Ok so my long fin serpe tetra has completely lost his tail fin. Its been about a week and I expected to see a change but nothing. Water is perfect and all other fish are healthy. Back of his body is now turning white. What do I do help!!! Thanks for your input.
This is the other serpe tetra

 

[Delapool]

You'll need to separate that fish to a QT and treat ASAP for fin rot and fungus as well. Once the tail is lost to the base, it may not grow back. How are the rest doing - the tail on the other looked a little ragged but hard to tell.

Water changes will help but in advanced cases you will need meds. Can I ask what your water conditions are for ph, ammonia, nitrite and nitrate to finish off. I would increase pwc's but depends what you are doing at the moment?

Are you getting any fin nipping or any other tank change. How long did it take for the tail fin to go?

 

[Spencer1044]

The other fish are completely healthy. I recently took everything out of the tank and added new substrate under the gravel. The ph is 6.8. Nitrite 0 nitrate 0 ammonia .25. It has co2 injection and I do water changes every 2 weeks.

 

[Delapool]

The other fish are completely healthy. I recently took everything out of the tank and added new substrate under the gravel. The ph is 6.8. Nitrite 0 nitrate 0 ammonia .25. It has co2 injection and I do water changes every 2 weeks.

Thanks for the information. I would increase pwc's to once a week and do 30 to 50% change. Also check fish food quality, general tank conditions for stress like nippy fish and water temp is correct. Mainly I've had it as a low grade bacterial infection years ago which slowly progresses but if chunks were rapidly lost or large, deep cuts appeared quickly it might be columnaris. I've copied a link below. If you let it go it can progress to other fish.

http://freshaquarium.about.com/cs/disease/p/finrot.htm

I'm guessing the tank works may have started a mini-cycle. Although ammonia is fine with that ph pretty much it would be nice to get it back to 0.