Parasitic skin flagellates swim in the aquarium until they find a fish host to adhere to.
Oodinium pilularis (as well as with "Ich" Ichthyophthirius multifiliis) it eats into the cells of the epithelial layer of the skin and fins as well as through the mucous membrane in the mouth. The mature parasite then leaves the host and drops to the bottom of the aquarium or plants. It then forms a cyst that divides, forming between 34 - 64 new cells, then bursts freeing the new cells into the aquarium to find a fish host.
Oodinium limneticum is similar, but attacks the fish’s skin and fins rather than burrowing under the epithelial layer, so it is localized right on the surface. It also multiplies on the host rather than at the bottom of the aquarium or on the plants.
· Yellow or light brown peppery coating. Looks like dust
· Clamped Fins
· Fast gill movements (respiratory distress)
· Cloudy eyes
· Weight loss
· Rubbing against substrate or tank décor
They can be treated either in the separate or in the main tank. A good treatment is with copper sulphate at 0.2 mg per litre (0.2 ppm) to be repeated once in a few days if necessary.
Aquarisol is one medication of this sort that is usually readily available. Acriflavine (trypaflavine) may be used instead at 0.2% solution (1 ml per litre). There are things to be aware of with each of these treatments however.
WARNING :Acriflavine can possibly sterilize fish and copper can lead to poisoning, so the water should be gradually changed after a cure has been effected.