Columnaris

Fluffy white or gray patches on skin.

Causes:
*Sudden increases in water temperature.
*Overstocking.
*Infrequent water changes.
*Low water oxygen (O2) content.
*Elevated nitrite levels.
*Uneaten food in the tank.

Fungus

Very similar to columnaris but you see it is a bit different. It appears on open wounds and grows on the dead tissue.

Causes:
*Fungi spores are naturally present in water.
*Previously damaged by some other parasite causing an open wound.

Ich

*Captive fish that develop ich usually get the disease when their immune systems are not functioning well.
*Stress caused by tank conditions, transporting.