fins blackening

Question
I have two small cross bread goldfish in a fish bawl. I got them five days ago. Now their fins are blackening. there are a few black splotches on one's belly. It might be from chlorine poisoning. But i want to be sure. The fish with the splotches doesn't seem to eat very well. Its scales aren't raised. Both fish have black fins.
There is an oxygen pump for oxygen(only on at night);
is regularly cleaned after the symptoms appeared;
fed once a day;
No salt used for the tank;
do not know pH values.
Please reply soon.
Thanks Km.


Answer
It sounds like your goldfish has/had ammonia burns.  The black is the gold fish healing.  Goldfish CANNOT live in bowls, you need a MINIMUM of a 20 gallon tank with a filter 2 times the size because of the mess these fish make.  I would take that fish back and get a Betta, these fish are better suited for bowls.  Please do some homework on goldfish and you will quickly see that this fish, when put in bowls, are quickly condemned because of how messy they are.  That should NEVER have been allowed to be sold as fish that can survive in bowls, it's the FURTHEST thing from the truth!!

Good luck.