Scales Turning Black ?!

[Guest Pylie]

Please Help,

I have 4 goldfish in a tank with a decent filter and a water change every 2 weeks.

Over the past 6-7 days the largest and oldest Goldfish has started to develope black scales a black leading edge on it fins.

Why is this and how do you get rid it ?

Is this life threatening ? or is 3 years for a goldfish old and its come to an end ?

Thanks for any info .........

[Guest OzzMosiz]

What size tank do you have? You should probably change the water at least once a week - depending on stocking levels. Black marks are usually a sign of ammonia burns healing. Check your water paramaters ammonia, nitrites, nitrates ASAP.