wanderlust2480@yahoo.com

Question
I recently (2-3 weeks ago) brought home a bubble eye goldfish and since then have been noticing a darkening of his fin edges. It started on his tail and is now on the rest of his fins except the pectoral ones. Fish
acts fine and is hungry. Right now he is the only inhabitant of a 20 gallon tank with heater (off because the temp is 65-70 without it) and water filter/aerator, full hood, etc. I am not overfeeding, I don't
think.  I've done two partial water changes, about one every week and will be cleaning gravel soon. pH and various levels seem ok. Ammonia is low or non existentant although it appears to spike every day or two...??? (I use tetra aqua ammonia detox and also condition all my water before putting in) I have salt in his tank right now and have a couple of friends waiting to join him, but I'm not sure if he is just maturing or has some sort of
illness. I thought that it might be fin rot, but it is dark brown/black, not white. I do have a picture and would appreciate your help. You can see the picture at http://photos.yahoo.com/wanderlust2480 under Fishy. I am trying to post a zoomed in picture.

(wrote that about 4 days ago). His tank mate has developed a small case of cloudy eye and I did a water change (~30%), have not added more salt, and now is being treated for fungal infections/cloudy eye. I figured I might kill two birds with one stone this time. More blackishness has developed, but still clueless.

Thanks!


Answer
Hi Erin,
If your ammonia is spiking you need to do very frequent water changes. Remember that goldfish are considered very dirty fish and will need to have alot of water changes or you will have very sick fish.  You must keep the ammonia at 0 and if your tank hasn't completed cycling it will take alot of work. Keep testing your water and if there is any spike immediately do a 50% water change to prevent damage to your fish. Bubble eye goldfish can really have problems with water conditions since they have the large eye bubble. Don't depend on any chemicals to totally control water conditions, only frequent water changes can do that. Since one of your other fish already has cloudy eyes you really need to watch your water conditions so nothing happens to your bubble eye. If you are already using a medication for the cloudy eye make sure that it doesn't kill your good bacteria off and you will cause your tank to have to start recycling all over again.You might need to buy some beneficial bacteria at the fish store just in case. Just keep an eye on your tank conditions. I looked at the pictures and it doesn't appear that your fish has any fin damage, just a darkening. It could be that it is just his color changing.I have had this happen before. Watch it closely just in case it develops into something else. It is really hard to make an accurate diagnosis of an illness in fish if they don't have many symptoms, that is why you are really going to have to observe and evaluate any changes. Just watch that water. I know I keep repeating myself about keeping the water very clean, but I know that if you don't goldfish will get sick very quickly since they pollute their water very quickly. Also, please don't overstock. Really it is better to have only one goldfish for every 10 gallons of water.  I only have two in a 29 gallon and have to do water changes of 50% twice a week.
Keep an eye on him and also be very careful not to overfeed. Best of luck.
Hope this helps,
Karen