What can I do to eradicate fin rot

Question
QUESTION: Hello Ron,

I hope you can help me. I have an 11 gallon tank tropical tank. The
temperature is at 24 degrees celsius, the ammonia and nitrite levels are at 0
but the nitrate levels are a little high. I have a few mountain minnows and
danios, a couple of platies and a couple of black skirt tetras (at least thats
what I believe they are). Also 2 dojo loaches which I bought years ago when I
had no idea what I was doing. Most of the tank has been infected with finrot
=[ My female dojo loach is on her last legs.

The only thing I can think of is that it is either over-stocked (although I
imagine the water quality would be horrendous) or that the slight PH change
has affected them. I recently moved to the other side of the country with them
(stressful for all of us and lost a few fish to shock) and have been using water
from the water butt outside for the water changes which has dropped the PH
from around 7 to more like 6.5.

I have been treating them with aquarium salt (once a week but not too much
cos I realise the loaches don't like it), carrying out 2 water changes a week
and treating them with Interpet Anti Fungus and Finrot No.8 with each water
change with no signs of improvement and just slow rotting of all my poor
fishes. I have read that increasing the temperature every few days and
decreasing it will help but I thought that would stress the fish even more.

I guess all in all, my question is,

What is causing this disease to strike at my tank? And how can I make them
better?

I can't afford a hospital tank being a student but I am willing to do anything to
help my babies.

Thank you for you time and I hope you can help
Yours sincerely
Rachel

ANSWER: Hi Rachel,
 Hmmm... in my experience, most cases of "fin rot" are not fin rot at all, but rather the result of one fish biting the fins of another fish. Do ALL the fish show signs of this, including the most aggressive fish?

 It does not sound like your tank is overstocked at all.  

 I am concerned about all this salt you are adding. Salt does not go away, so every time you add salt, you are increasing the salinity of the water.  Personally, I NEVER add salt to freshwater fish tanks. Ever.

-- Ron C.
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>



---------- FOLLOW-UP ----------

QUESTION: Well now you mention it. None of the minnows seem to have any problems
and they are the least aggressive. Only the tetras and male platy seem to be
missing fin and tail and they often display and peck at each other. My female
loach only contracted it after spending 24hrs behind the chest of draws last
week after managing to squeeze out the lid. Her tail has definitely rotted
away. The hole has been tapped up since.

I have only added 5 teaspoons of salt but I will cease this as I always had my
suspicions about it.

What would you suggest? I was thinking of continuing the treatment for
another week and then leaving them to see how they get on.

Thank you for your help

Rachel

Answer
Hi Rachel,
 Re: the loach.  When a fish "goes over the wall" the fins often dry out and fall off. Fortunately, they typically eventually grow back.

 I would stop adding the salt.  I would add more plants to the tank to break up the space and perhaps reduce the amount of chasing and pecking.

-- Ron C.
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>