fish illness

Question
QUESTION: I have several tanks, a 75 gallon established for almost a year and a 20 gal that I have had only 2 months. The first fish I put in the 75 gallon where 5 Mollies. They did very well, had babies and remained healthy as I gradually added more fish (Cory catfish, cherry barbs, rainbows, gold tetras, and clown plasticumos)then one at a time, the yellow Mollies developed black rings around one eye and one or two black spots on their head or body. They lived for a couple of months with this and then died. I cannot seem to find an answer as to what is causing this! I have the one remaining yellow molly who has now developed the black ringed eye, two small irregularly shaped black marks on and near her head, a bright orange lower lip, and red gills. I have her in a hospital tank and have treated with Maracyn-two and Maracide according to label instructions for 5 days with no signs of improvement. The fish's behavior is also a little different, she swims constantly in erratic patterns like she's looking for something that she can't find! Her gills are flared and her fins are almost transparent but do not look damaged, dorsal fin has the same bright orange area as the lower part of the mouth. Should I continue with the treatment even though the instructions are only for 5 days? Should I try something else? I also have a fancy guppy with a dark eye and red gills in the tank.

Thank you for any help you can provide!!

ANSWER: Hi There,

All of these symptoms are usually caused by poor water quality. The black marks on their body suggests ammonia burns that are healing.

The best way to go about this is to change the water daily or every other day, to bring the ammonia levels down.
I would stop the treatment as it will just cause more stress to the fish.
You should see an improvement in the fishes health very soon if the daily water changes are provided.

Hope this helps
Chloe :)

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

QUESTION: Thanks for your quick reply. I have been checking the ammonia levels and they are okay, I also took water from the separate tanks to my local fish store to be tested and they said that everything is fine. Is there anything else that this could be? Almost all of the blackness is in a circle directly around the eye with only 2 very small smudges on the head. Will frequent water changes overstress the fish if they are unecessary? Should I return the fish to the tank with the others of keep it isolated?

Answer
Hi,

If water quality is fine, this is probably the natural colouring of the fish.Goldfish tend to change colors. Some reasons goldfish change colors are:
1) changes in temperature (warmer temps will cause fancies and especially black moors to turn orange/bronze)
2) diet will impact a fishes coloring
3) Many large pet stores (and smaller ones) sell goldfish that are 2 - 3 years old. At this age, it's hard to tell exactly what color or colorS your fish will be.

Hope this helps,
Chloe :)