Lupin;3897507; said:
It's not fungus nor ich. A good guess is bacterial infection or water quality-related issue itself, most likely parasitic in nature.
The first flaw here unfortunately is your failure to quarantine the JD. You should not introduce new fish to your current stock WITHOUT quarantining the fish for at least 3-4 weeks. You risk infecting your oscar in the process from failure to do so.
Can you please answer the following questions? Copy and paste the new questions in your new reply post.
I understand that I didn't qt the JD, but I just don't have any space for it unless I set up a 4 gallon tank using my water changing bucket...
1. What is the size of your tank? 55g
2. What are your water parameters? State the brand of test kit used. Ammonia is 0, I don't have a nitrite or nitrate test kit, but the tank has been running for nearly a year and this is the first disease that's ever occurred. I keep up with weekly water changes.
3. Is your aquarium set up freshwater or brackish water? Fresh
4. How long the aquarium has been set up? Since March 09
5. What fish do you have? How many are in your tank? How big are they? How long have you had them? The only fish I have besides the JD is an oscar, eyeballing it, it's at 6" without the tail. had it since ~middle of last year
6. Were the fish placed under quarantine period (minus the first batch from the point wherein the tank is ready to accommodate the inhabitants)? No, no tank space
7. What temperature is the tank water currently? 76 F
8. Are there live plants in the aquarium? No
9. What filter are you using? State brand, maintenance routine and power capacity. Two marineland penguin 350 hob filters, 700gph total/rated 150 gallons total
10. Any other equipment used (aside from heater and filter which are two very important components of the tank)? No
11. Does your aquarium receive natural sunlight at any given part of the day? What is your lighting schedule (assuming you do not rely on sunlight for our viewing pleasure)? No
12. When did you perform your last water change and how much water was changed? How often do you change your water? Do you vacuum the substrate? Water changes every sunday, 28-35%(4 or 5 buckets), I vaccum the substrate for the first two buckets.
13. What foods do you provide your fish? What is the feeding schedule? Just got the JD recently 36 hours ago, hasn't eaten yet
14. What unusual signs have you observed in your fish? New JD so I don't know any normal patterns, but hiding in the bottom of the tank doesn't seem that usual
15. Have you treated your fish ahead of diagnosis? If so, what treatments did you use? State your reasons for planning ahead of proper diagnosis.
Underdosed with 3-4 tbs of salt because of recommendation above your(Lupin) post
Thanks