"mort" wrote in message
...
Yup. Black edges to the fins is the sign of too much ammonia in the tank
water. Immediate remedy is do a large water change to get rid of the
ammonia.... 'til you cycle your filter properly.

I think that the OP might want to actually *check* the ammonia levels. My
NewFish has some black on his fins, and my ammonia is at 0. I think it's
just his coloring.

A