Sick Fantail Gold fish

Oct 22, 2002
23
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#1
I really need some help. One of my fantail gold fish is really sick. I've had him for almost a year. I'm not sure what it is. I noticed a black mark like a streak on his side about a week ago. I used some melafix for a few days, but now it looks like it has bruises on the underside of his belly and the black streak mark is starting on the other side. He didn't seem to be sick, but now he is not swimming so well. I have checked the amnonia, nitrites and ph of the water. All levels are good. Please help. Thanks in advance.
 

colesea

Superstar Fish
Oct 22, 2002
1,612
0
0
NY USA
#3
Black streaks have always been due to some form of rapid change in the water chemistry, either ammonia toxicity or just a really really dirty tank that finally caught up with the fish, in my experience. Nitrate toxicity usually catches up with a tank that hasn't been water changed in ages.

How often are you doing water changes? What size tank is it? How big is the fish and what color? Do you have any carbonate based decorations (shells, corals, tufa stone, Etc) in the tank? Are their any tankmates? When you say the levels check out, what are they?

Goldfish like large volume water changes very frequently. I do my own goldfish tank 10 gallons twice a week. I also add a small palmful of aquarium salt (not a whole heaping palmful, just a small one) once a week to help prevent fin rots. Mine are going on three years.
~~Colesea