antisocial fish

Question
Hi again. It's not anti social behavior, now they have red spots on their gills and blood streaks on their tails and fins. Their behavior is the same, they still eat and such. We've removed the fish cause not only did the water that was added w/that new fish put pollution in the tank but the new fish was almost biting or picking at the old fish despite how small it was- so we removed him. We got some Maroxy and it's been 2 days since we've been adding it everyday but it doesn't seem to be doing anything. It says for fungal and some bacteria. Is this the wrong stuff? From what we've read about the symptoms, it seems to be dropsy......? Does this sound about right?

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Followup To
Question -
We've had 3 goldfish for about 2.5 yrs. We just purchased a new goldfish at Wal Mart and added him (after letting him set in the water in his bag for about 15 minutes). The first day the other fish were fine and eating fine. Now the second day we woke up to all the fish (including the new one who's a lot smaller but not eatable to the other fish)behind a rock in the corner at the bottom and they just sit there. They're normally very social fish and when we fed them they all ate, but then they go back into the corner and the new fish is out and about his own business. What do you think the problem is? Also, to add to this stressful issue, the old fish were just transferred from another house about a week prior to the adding of the new fish), including an all new tank water change but the fish were fine until the new fish was added.
Answer -
Hi D;

The other fish are probably feeling shy with a 'new kid on the block'. Give them a couple more days to get used to each other.

Look carefully at them to be sure they don't have spots, dots or anything else irregular. Sometimes a new fish is immune to a parasite or other disease it carries. The fish already in the tank get sick, but the new one doesn't. I think they're probably just trying to get used to each other, but you just want to watch and be sure.  

At Your Service;
Chris Robbins

Answer
Hi D;

They are infected with bacteria and it has caused a very serious symptom called "Hemorrhagic Septicemia". The infection has attacked the blood vessels themselves. Make a 25% water change to reduce toxins and treat with "Maracyn 2". MarOxy is much too mild and can't absorb inside the fish to get where the infection is. You don't need to use it anymore. The Maracyn 2 will get inside and treat it. Or, use a medicated food that contains tetracycline. Don't use both Maracyn 2 and medicated food at the same time. It could overdose them.

The excess waste from the new fish bag water has probably caused ammonia to rise, and it stressed the fish enough to be susceptible to it. Whenever you buy new fish, net them out and throw away the bag water. I can't say for sure that the new fish brought it in, but it's possible.

Here is more about it;

http://www.geocities.com/shtinkythefish/diseases/septicemia.htm
http://www.petlibrary.com/goldfish/septi.htm
http://www.fishbase.org/Diseases/DiseasesSummary2.cfm?discode=157

I hope they feel better soon. It's so hard to diagnose without actually seeing the fish. I'm glad we were able to get this figured out!

At Your Service;
Chris Robbins