please help - i have a poorly fish...

What that someone told you is true - that almost assuredly is why the fish
got sick in the first place. I am sorry to break it to you but you really
should only have one or 2 of these fish in your 15 or 20 gallon (u.s.) tank
(100 liters equals 15 or 20 u.s. gallons, right?)

100 liters equals 26.4172051 gallons, to be precise. One would be
rounding off a bit, but at the ratio of one goldfish per 10 gallons,
having three goldfish in such a tank should be fine. I wouldn't push it
further than that though.

- Logic316



Q: How many liberals does it take to screw in a light bulb?

A: One liberal and twenty eight delegates representing all the social,
economic, and ethnic communities.
A: Two-one to do it and the other to keep the first one's knee from
jerking.
A: None: They can't remove the old ones since they are already part of
the environment.