A Closer Look at Black Spot Disease – Part 1 (Ammonia)
There are two very different fish diseases that get called ‘black spot disease.’ One is caused by healing after injury (most commonly ammonia burn), and the other is caused by a parasite that infects the intestine of birds.
Ammonia burn
Most examples of black spot disease in aquariums are the result of ammonia burn on the fish’s skin or fins. When the affected areas start to heal, the small patches that recieved the harshest burn turn a dark brown or black colour.
The black spots themselves appear as discoloration of the skin, rather than something in or on the skin. They can range in size from barely noticeable to a “rolled around in black paint” look, but are usually small smudges.
Blackened skin from ammonia burn is actually a good sign. It means the ammonia has dropped back to a safe level, and the fish’s skin has started to heal.
However, it is a worrying sign that the ammonia level was raised in the first place. Action needs to be taken to minimize the risk of raised ammonia. A lot of fish that suffer ammonia burn don’t get the chance to get black patches on their skin. They get killed instead.
Spot the signs
Fish in a tank or pond with high levels of ammonia will gasp for oxygen at the surface, float on their sides, sit at the bottom, lose their appetite, get red streaks in their fins, develop reddening around the gills, and/or make swimming look like hard work.
As soon as any of these behaviours are spotted, get the water tested to confirm ammonia poisoning and take action to remove it.
Removing ammonia
Changing the water is the best way to get rid of ammonia. Do it every day until the ammonia levels are down to an acceptable level i.e. less than 4 parts per million. An ideal level is less than 2 parts per million.
The other option is to use chemical treatment, but water changes are obviously better as they do not involve adding further chemicals to the water.
Prevention
Test the water regularly, and change it regularly. High ammonia levels are a sign of a badly managed aquarium.
Do not overstock. Too many fish produce too much waste, which contains ammonia. If the filter can’t cope, ammonia poisoning is inevitable.
Do not overfeed. Uneaten food decays, producing ammonia.
Use a treatment tank if the water needs to be medicated. Medications for unrelated fish diseases can kill the bacteria in the filter that remove ammonia from the water.
Keep a very close eye on new tanks. Ammonia poisoning occurs most often in new tanks. Ammonia will peak at the end of the first week. It is advisable to start with only one fish so waste is kept to a minimum.
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June 13th, 2009 at 7:15 am
This is a great article that should be promoted much more. Unfortunately, this characteristic of goldfish is not well known to people and surprisingly a large amount pet store keepers.
August 10th, 2009 at 12:17 am
I did have high ammonia and did a water change as well as treat for ammonia. One week later, my weakest goldfish (purchased over one year ago as a tiny feeder fish) has the black symptoms and is lying upside down and struggling to breath.
Is there anything to save this fish? I separated him into a bowl and addes some stresscoat. What should I do to save him?
August 11th, 2009 at 4:37 am
i have two goldfish, one of them is new, the other i have had for one year, i put them in the same water thing after making sure my new fish was not sick by keeping them seperate for a week.
Now my first goldfish(after they have been in the same tank for like, two weeks)is kinda fat by her abdomine(pregnant maybe?)
and she was just orange and white
then the other fish , the new one, stared getting kinda dark under its left front flipper thingy
now its black on all its tails\flippers, and it almost looks like its black from the inside
im scared that my fish might both die cuz in less than two hours my old fish has gotten a black spot on its tail fin
and when i woke yesterday morning they were both bleeding, even tho i am feeding them regularly
they were both bleeding on their mouths and my new one (whose name is King)is bleeding under its mouth and under one of its from fins
please please email some kind of info at katluvr12@gmail.com
please tell me any suggestions u might have cuz im desperate
September 21st, 2009 at 3:17 pm
Are there any goldfish diseases surrounded an eye of the fish. My goldfish che-che has one black eye and the other is normal. This happened about a week ago, and I dont know what caused this to have happened. Can you please, let know me know if theres info about this and I how I can get him well again. Thank you so much. Amanda
December 1st, 2009 at 1:03 pm
hi my fish was yellow but now he is half black someone help me
January 3rd, 2010 at 6:14 pm
i have two goldfish. They both have red color lines(seem as if blood has come under the topmost layer of skin in the form of lines and not spot) around there mouth. The smaller one is the first one to have it around its mouth. The other has got only on one side.
Plz help and suggest some measure.
January 5th, 2010 at 12:21 pm
Hi,
My 5 year old goldish has deveoped a black top lip, like a mousetach, otherwise it seems very healthy, can any one tell me what this is please.
Best Regards,
Graham.
May 22nd, 2010 at 10:03 pm
this atrical is very helpful i was looking up goldfish diseasea for my
mother when i ran across this one it explaned everything i needed to know..
thank you and keep up the great work..
July 27th, 2010 at 4:25 pm
after noticing my goldfish acting very strange, 1 flipped itself out of the tank and 1 buried its head into a rock, i had no idea why it seemed my fish were trying to commit suicide!! they looked very poorly, frayed up fins and some lying still at the bottom.. i searched the net and after reading your write up, i discovered that my aquarium had high ammonia levels which was burning the fishs fins and hurting them so much that they were trying to free themselves from the polluted water!! immediately after reading this, i did a full water change, bought a new larger filter adequate for the tank size and even purchased a plant as i figured it would allow more oxygen to enter the water.. one week later and thank goodness they look better!! the fish with the most damage, its fins have now turned black, a positive sign of healing and they are all eating well and remain active.. i am now keeping a close eye on them all and am going to invest in an ammonia tester and an aquarium vacuum which cleans the gravel as i now know the high ammonia levels were caused from build up of the fishs waste.. i cant thank you enough.. if people were more clued up on how to look after fish, when they are purchased from stores it may put a stop to alot of pain and suffering the fish have had to encounter x x