Please provide the following details when requesting help for Goldfish Problems:
Test Results for the Following:
Ammonia Level? 0-.25
Nitrite Level? 40
Nitrate level? .5
Ph Level, (If possible,KH and GH and chloramines)? 8.0
Ph Level out of the Tap? I don't know.
Tank size (How many Gals) and How long has it been running? 21 gallons H
What is the name and size of the filter/s? Top Fin for 40 gallon aquariums. Change every month.
How often do you change the water and how much? Not often enough. Like once every two months.
How many fish in the tank and their size? 2 small fantails
What kind of water additives or conditioners? None, just added salt today
Any medications added to the tank? None
Add any new fish to the tank? None
What do you feed your fish? Colorfin - Tetra
Any unusual findings on the fish such as "grains of salt",
bloody streaks, frayed fins or fungus? Yes, large bright red spots on head, body, tail.
Any unusual behavior like staying
at the bottom, not eating, ect..? No.

I have two great fish that I've had in the same tank for around 6 months. My white one has doubled in size while the one with the new spots has stayed the same size. I've done nothing different but last week he has developed bright red, large spots on his head, body and tail. They very bright and I can only assume they are blood. My other fish has not spots (yet).

This is my office tank and unfortuately, it is by a window and it does get a buildup of algae that I scrape once a month but other than that I keep an eye on the nitrate/nitite level.

I has been a good deal warmer here recently.

I'm worried since I lost a previous tank to rampant tail rot (not goldfish and about a year ago). Any ideas?

Is there an airstone in the tank to give extra oxygen in the heat?

The spots sound like something bacterial. Do they look like bruises? Is fo then its septiceamia and you would need to do 50% water changes for the next few days. And then twice weekly until the infection is gone and buy a gravel vac to keep the gravel clean as most bacteria lurk there.

If the spots look like acne then you will need to get your tank tests in order. You need ammonia at 0 nitrites at 0 and your nitrates at around 20. I think you have your nitrites and nitrates the wrong way round.

Once you get the water in good shape hopefully your fish will get better without any medication.

Do you throw away your filter media and the place in a new one? Is it a sponge at all? If so then just squeezing it out once a week in old tank water is enough.

Please keep us updated.

welcome to the forum too

Any news?