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Black Smudge

Guest dutoits

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Guest dutoits



If you could have a look at the photos and identify the problem it would be great.

The photos were taken 3 days after I first spotted a tiny black smudge. It is now 5 days later and the smudges are now twice as much and twice as big.

This is very longwinded but I tried to be very specific so that you have all the info!

Over the last week the very tame nine year old comet goldfish, who was never before sick or anything, has developed small black marks on the tips of his tail and lower back fins. It is getting larger every day. It started of with a couple of pin sized marks on almost all fins &tail.

Only two things happened over the last 2-3 weeks that was out of the ordinary.

A newish fish started nibbling on his fins. The fish was removed as soon as we noticed who the culprit was. Although upsetting, the damage done is really not a lot, a bite out of the end dorsal fin and a small one out of the bottom fin. His tail fin had a couple of nibs out and a fairly long tear, (the tear is already completely closed up).

He has been a little off for a couple of days after that, (clamped dorsal fin, just lying on the bottom, not the normal huge appetite) so I dosed the water twice with a broad spectrum antibiotic that I had and two days later a dose of Tetra medica General tonic concentrate, all according to instructions on bottles. The Comet was his old boisterous self again after the second day of treatment, eating well and frolicking about whenever he sees us, and is still looking very happy.

For this past week I've been doing water changes every second day (about 25 - 30%), and dosed for the last 3 days with tetra fungistop, as suggested by the local fish shop, the bottle is empty, but the spots are definitely spreading.

I also saved the water readings on the day I took the photos

ph : 6.2 - 6. 8

nitrite : 0 - 0.5

nitrate : 160 - 200

alkalinity : 40 - 80

ammonia : 0 - 0.25

temp: 26 (Was put up a bit as suggested while he was under medication)

I read the following on the internet, but the photo shows a fish with lots of black all over. http://www.koivet.com/html/articles/articl...7&name=Diseases

"Blackening and dark spots occurring on goldfish after some trauma to the skin will usually resolve in 3-6 weeks."

Most other links I found are also not very definite about treatment.

Hope someone has seen this before, a definite answer would be appreciated.

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  • Regular Member

Could they be ammonia burns? I notice that you do have small traces of ammonia in the tank.

As for the clamping fins, Doc Johnson states in his book 2 reasons for this.

1. A ph drop or crash

2. Flukes

Could either of these be the cause of that??? I did notice your ph was a little low, is it always that way or is this new?

I too didn't see the photos.

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  • Regular Member

Hi there - would you be able to retest your nitrates? They're astronomically high and at this level, could cause so many problems with your fish, i wouldn't know where to begin :blink: .

Hopefully it's a mistake though :) Nitrates should sit <40.

And if you've been doing waterchanges, they will have come down but you'll need to do several before you fall into a 'safe' range.

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