All four fish were being kept in about 2 cups worth of FILTHY water, previous to me acquiring them. I don't know how long the fish lived in this tiny "aquarium", or where they came from. The tiny container looked like the kind of thing you could win at a state fair.
I know a 5 gal. tank is...
I'm not a beginner when it comes to keeping goldfish. I have a small (550 gal.) pond outside, and a small aquarium in the house.
I'm having a problem that's a real stumper.
About 3 weeks ago I started a small tank (5.5 gal) for 4 small common goldfish, the largest about an inch and a half...