Dalmation Mollie Disease

Question
Hello, I have have a Dalmatian Mollie for about 8 months and all of a sudden it has gotten sick.
-8 months
-10 gallon tank
-1 dalmatian mollie, 1 "mickey mouse" fish, 2 neon tetras, 1 guppy, 1 unknown livebirth-probably guppy
-some type of "silent" filter where the water goes through the filter and falls out the top
-pH, ammonia, nitrate unknown
-no water changes. 25% evaporates every 2 weeks. I just add more
Question: I noticed tonight that my mollie has raw areas on top of each gill. It looks like a large red spot with a thin white line around it. Outside of that there appears to be gold flakes. The skin is not bloody just raw. It almost looks like a red chicken breast. It also has sagging fins and hides by itself in a small decoration near the bottom. It only comes out to feed. It also looks like it has some trouble swimming, shaking back and forth. None of the other fish appear to have any problems.
Also, there is a small amount of algae buildup. Within the last week I have: Added 2 gallons of water treated with Jungle Start-Right, Used 1 tablet of Jungle Algae-kill and added 1 tsb aquarium salt. I hope this gives you enough information to help. Anything you could offer would be appreciated. If needed I could attempt to take a picture and post it somewhere online where you could view it. Thank you.

Answer
Hi Josh;

It sounds like a bacterial infection has attacked your molly. It will need antibiotics. See what your local fish store has for it. You just drop the proper dose in the tank water. Maracyn or Erythromycin would probably work. It would be good to also get some Melafix to help heal the open wounds caused by the infection. Melafix helps re-grow damaged tissue and helps inhibit further infection. It isn't strong enough to cure it though. The antibiotics will still be needed.

Bacterial infections like these get started from lack of water changes causing high nitrate levels. The water quality must improve or the fish cannot heal completely or permanently, even with the medicine. Nitrate is a toxin that is the "end result" of your tank's biological filtration. It is only removed by manually taking water out of the tank. Evaporation leaves it behind. Nitrate will be at very high levels now after 8 months and the immune systems of your fish cannot stay strong with it so concentrated. To correct it and get back on track make a series of partial actual water changes, siphoning out and removing 25% of the water. Do these 25% changes every other day for a total of four changes. You will then be ready to cut back to only once a week. You will notice a big difference in the health and vitality of your fish too. It's perfectly okay to make these changes with the medicine in the water. Do them right before that day's addition of medicine. Don't worry that some of the medicine is being removed when you change the water during the treatment period. Once the medicine has been in the water for more than a few hours it is decayed and is okay to remove with the water change the next day. That's why it has to be added again every day.

Salt is okay to use while the fish is healing but mollies really don't need it. I used to think it was necessary too but it's an "old school" attitude that has been proven obsolete. They just need clean fresh water to thrive. Breeders of mollies and other livebearing fish actually change water every day in their tanks. Their fish grow very fast, rarely get sick, and they don't need salt because they get all the minerals and electrolytes from the constant supply of fresh water.

I hope your fish feels better soon...

At Your Service;
Chris Robbins