sound like you may have velvet disease:
read this:
The name sounds nice, but don't be fooled. Velvet is one of the more common diseases in aquarium fish, and can strike down every inhabitant in the tank before the hapless owner realizes what he or she is dealing with. Also known as Rust or Gold Dust disease, it is caused by one of several species of a tiny parasite known as O?dinium.
O?dinium is a dinoflagellate, a creature classified by some as a protozoan and by others as algae because it contains Chlorophyll. O?dinium doesn't care how it's classified, it's an equal opportunity parasite that stikes fresh and saltwater fish. In freshwater fish Velvet is caused by either O?dinium pilularis or O?dinium limneticum. In marine fish O?dinium ocellatum causes the dreaded Coral Fish disease. All three species have symptoms and lifecycles similar to the well known parasite, Ich.
O?dinium finds a fish and adheres using flagellum, then forms rod pseudopodia which penetrate the skin and soft tissues of the gills. The pseudopods destroy the cells and feed on the nutrients inside. After feeding and maturing, the parasite drops off the fish and divides into dozens of cells that are released into the water to seek hosts. They must find a host within 24 hours, or die.
O?dinium produces white pustules on the fish that are much finer than the spots seen in Ich. In fact they are so fine they are often not seen before the fish perishes. Like Ich, O?dinium is present in most commercial tanks, but only becomes a problem when the fish are stressed by poor quality water, changes in the water temperature, or being transported.
Symptoms:
Scratchs against hard objects
Fish is lethargic
Loss of appetite and weight loss
Rapid, labored breathing
Fins clamped against body
Fine yellow or rusty colored film on skin
In advanced stages skin peeks off Initially the fish rub against hard objects trying to dislodge the parasites. As the disease progresses the fish becomes lethargic, fins are held close to the body, appetite is reduced and the fish loses weight. A key symptom is difficult breathing, resulting in rapid gilling.
Perhaps the most telltale symptom is the appearance of a velvety film on the skin that resembles gold or rust colored dust. The film may be difficult to see, but can be more easily detected by directing a beam of a flashlight on the fish in a darkened room. The parasite is most often seen on the fins and gills. Velvet attacks all fish and will even affect fry that are only a few days old. Anabantoids, danios, goldfish, zebrafish, and killifish are particularly susceptible to velvet disease.
Treatment :
Raise water temperature
Dim lights for several days
Add aquarium salt
Treat with copper sulphate for ten days
Discontinue carbon filtration during treatment
Because Velvet is highly contagious and usually far advanced before being diagnosed, it is important to take steps to treat it as soon as possible. Treatment is targeted at the free-swimming stage of the parasite.
Copper sulphate is the treatment of choice. It should be used according to the manufacturers instructions for a full ten days to ensure that the parasite is completely eradicated. Atabrine (Quinacrine hydrochloride) is another medication that can be used to treat Velvet.
Because O?dinium is dependant on light, dimming the aquarium lights aids
