Accepted Answer

HI again and thank you for the information.

 

There's a few things going on here so I'll be commenting/advising on a variety of topics with regards XX XXXX tank's situation.

 

The first thing I'd like to touch upon is the use of RO water. Unless you have unsuitable source water, using RO water isn't really necessary and might even be depriving the fish of necessary minerals contained in dechlorinated tap water.

 

Keep in mind that as you've just done a complete 100% water change (75%=RO, 25%=tap water) the tank water will begin to cycle. I assume you're aware of the cycling process, if not, listed below is a link which will explain it.

 

Ok as for the problem(s). The symptoms you've described=swelling of the mouth and redness of the fins are an indication of a bacterial infection. The name for the disease associated with the redness (bleeding) of the fins is called Hemorrhagic Septicemia

which is internal bleeding/hemmoraging. You also mentioned the tank having a bout with Ick.

 

When a tank has chronic disease issues the culprit is usually unfavorable water conditions and/or the addition of a new fish who has brought a disease into the tank.

 

Unfavorable water conditions can be caused by the presence of ammonia and nitrites, high levels of nitrates and/or improper water conditions for the fish, i.e., too high of a ph for a fish that requires a low ph, too low of a water temperature for a fish that needs higher water temperature, etc. etc.

 

Assuming the water parameters, i.e. ammonia/nitrites/nitrates, are fine the way to treat this is to first make sure that conditions are suited to the fish, once again temperature and ph being the priority here. Once confirmed begin to treat the tank with a medicine called Triple Sulfa, click on 2nd link below for a view of the product, which can be found at most major pet stores where fish are sold. Just follow the directions on the product label for dosage.

 

Now keep in mind Tony that if the tank is cycling this becomes a whole different scenario in which the medicine will be ineffective and the fish will encounter a whole another set of problems due to the formation of ammonia and nitrites in a cycling tank

So this needs to be seriously taken into consideration.

 

On a final note. You mentioned that the nitrate level=-0-. This is extremely rare and borderlines the impossible in a fish tank. Generally one would only see this in a newly set-up tank or a tank that has just undergone a very big or 100% water change.

 

I'm not questioning the fact that this is the test reading you read but I'm wondering if the test kit might be expired or something. So what I suggest you do is when you test the water, right after testing it take a water sample to your local pet store (they'll usually test for free) and let them test the water and compare the results.

 

Best wishes and please let me know if you have any questions.

 

http://www.thetropicaltank.co.uk/cycling.htm

 

http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=4829

 

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Expert:	TROPICAL FISH AFICIONADO
Pos. Feedback:	99.5 %
Accepts:	1634
Answered:	5/27/2009

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OVER 20 YEARS EXPERIENCE W/TROPICAL FISH---BREEDING, MAINTAINING, CURING