It sounds like it's this, based on what I see....
Coral Reef Disease
Coral Reef Disease is one of the most common diseases of freshwater and marine fish, which can rapidly cause death if not treated promptly. The parasite primarily attacks the gills, body, and fins of the fish. The parasite, which is a small protozoan, is introduced into the aquarium through nonquarantined fish. The disease is rapidly transmitted from infested fish to other fish in the aquarium. During the life cycle of the parasite, it first develops on the fish's body and when mature drops to the aquarium bottom. The parasite encysts, then undergoes cell multiplication to form small free swimming parasites called dinospores. These young parasites are released from the cyst and infect other marine fish. Coral reef disease must be treated as soon as the disease is identified. A delay in treatment can result in the death of all your aquarium fish.
But it could be this based on what I'm reading here.....
White Spot Disease
"White spot disease" or "Ich", is a primarily cutaneous infection of freshwater and marine fish caused by the protozoan parasite Ichthyophthirius multifilis. Ich most often causes the appearance of small white spots over the body and fins of fish. However, it is important to note that Ich can present with many different appearances, and that other things besides Ich can cause small white spots on the body. Thus, the only sure-fire way to know that what you're treating is Ich is to scrape the skin of your affected fish and look at the scraping under the microscope. For those of you interested in looking at things under the microscope, Ichthyophthirius is a large ciliated protozoan with a U-shaped micronucleus. Its shape changes as it moves through the water, and it appears to "tumble" as it moves. For those of you not interested in skin scrapings, you can have a high rate of success just assuming that what you're treating is Ich. To effectively treat Ich, it's important to understand a little bit about the life cycle of the organism:
1. The adult stage lives on the skin and body of the fish. It will burrow under the epidermis, causing skin damage. Disruption of the skin leads to osmoregulatory disturbances, osmotic stress, and allows for the easy entrance of secondary invaders like bacteria.
2. The cyst stage lives on the bottom of the aquarium, and gives rise to about 300 tomites per cyst.
3. The tomite stage is the only stage which is sensitive to the medication! The life cycle takes 12-16 days to complete, depending on the temperature, and the tomite stage lasts for only three days.
All of these facts may seem trivial, but they are important because they dictate what treatments will be effective
