Strange white spots on black moor--?

The white bumps can be a sign of high nitrates. My fish usually get them when my nitrates start to get high.

I would recommend just a good water change of at least 50%.

You don't actually need to scrub the gravel, and it's actually better if you don't. There are beneficial bacteria on the gravel that help to convert ammonia to nitrates. A thorough cleaning of the gravel may ruin the colonies. A thorough gravel vacuum to get the crud out from underneath the gravel though would be beneficial.

Try not to stir up too much of the muck because sometimes anaerobic pockets can form under the gravel and when stirred up can be toxic for the fish. Just stick the siphon down into the gravel and twist so the dirty, decomposing stuff is siphoned out. Then pick straight up and move to the next spot.

You should test your water for nitrates immediately and change out the water needed to maintain a nitrate level of less than 20ppm.

---------------------

How many fish and what size tank do you have? What type of filter/equipment? And what are your water changing routines?

---------------------

Do not treat with a broad spectrum antibiotic. Antibiotics should not be used unless you know what you are treating for and the antibiotics are absolutely mandatory. Frequent treating with antibiotics for undiagnosed causes of symptoms leads to undue stress and a buildup of resistance to the antibiotic. This may lead to future medicating to be futile. This is same for humans and all other beings. Do not medicate unless you know the cause and you know which antibiotic you need to treat with.

More likely than not, the white spots are due to poor water quality and not a bacterial infection.

::EDIT::

With the additional details you've provided, I'm about 90% sure this is a water quality issue now.

Your goldfish, as it gets bigger, will do better in a tank of at least 20 gallons, if not bigger. Especially since the only filtration is an under gravel filter. (UGF). Goldfish produce a lot of waste, so you really want a filter like a hang on back power filter that turns over at least 10x the water volume. So for your 10 gallon tank, you want a filter that runs at least 100gph (gallons per hour). UGF in general can trap a lot of debris and muck which can also eventually cause disease.

The carbon filter, I'm sorry to say, doesn't do much for your tank unless you are medicating the tank. You need as much biological filtration as you can possibly put into a filter box. It will help break down ammonia (which goldfish produce a lot of.)

With a goldfish in a 10 gallon tank, depending on size, you should be doing water changes of at least 30-50% once a week (if not more water volume).

As I recommend earlier, check the water for nitrates and reduce whatever reading you get to less than 20ppm. A large water change if done properly, won't affect the goldfish as much as poor water quality will.

If you have any further questions, feel free to email me, or I would recommend joining a forum like the one on kokosgoldfish.com. The people there are very friendly, caring, and know a lot about goldfish.

Your local pet shop or aquarium are good spots to start, I usually ring them with symptoms when my fish look odd. Maybe it's something to do with the breeding cycle. I agree it doesn't sound like ick - I've just had that through my tank, and its not neat positioning on fish, but it might not hurt to treat the tank with a broad sprectrum anti-biotic anyhow - just in case. I was too slow in responding and lost my big gorgeous Silver Shark just after having got the bigger tank to accomodate his growth!