black spot on molly disease?

Question
I have had my 10 gal tank running for about 3 weeks now and stocked it witha  a balloon molly, lyire tail molly, and a platy. I have been treating for the past eight days with furan 2 for what my boss at work (I work at a pet shop) calls "the funk"  I suppose i just jumped the gun and added fish too soon. my levels on chemistry of the water were all fine-- im testing again tomarrow. I was essentially treating with furan for fin rot on my platy and now has started to regrow his tail. Im adding melafix too to aid in growth. now my balloon molly has a black spot on his dorsal fin and just today i noticed some small spots on his body .. what could this be? I don't want to have to treat with safeguard because i hear that its hard on plants and mine are struggling to bloom. the spot on his dorsal fin is about the tip of a ball point pen and the ones on his body are like flecks of pepper. i have been lately changing the water 25% about 2 times a week because of medicating with furan2. i have a whisper filter on my tank.  

Answer
Hi Lori;

I don't think they need medication. I think the spots and probably what looked like finrot were from the toxins that build up during "New Tank Syndrome", or could even be a natural color change. Ammonia is the first toxin that rises and it causes deterioration of fins and can cause black areas or spots too, known as ammonia burns. It is probably going down now as the tank continues to break in so they would get better just from that. Or, they really did have finrot and the ammonia made it worse. Either way, they are getting better.

The water changes are a very good thing to do right now and so is using Melafix. It will soothe the irritations caused by the toxins. When you have the water tested, ask them to test for ammonia (NH3) and nitrite (NO2). The ammonia is probably down or going down and nitrite is probably elevating. You could have the pH and nitrates (NO3)checked but they really aren't important at this stage. Here is a link to my page on new tanks so you know what's been going on in there and what to expect next;

http://www.xanga.com/Expert_Fish_Help

There is a remote possibility that the dots are from a parasite. It is a larval trematode rare in tropical fish though and requires a complex life cycle with mammal or bird hosts in order to survive. I really don't think that's what it is, but just something to keep in mind. If the spots are raised up like tiny grains of black sand, it's the trematode. If the spots are flat against the skin or scales, it's from ammonia burns or even could be a natural color change.

I hope they feel better soon...

At Your Service;
Chris Robbins