My First Tank
COMMON FISH DISEASES 
Tail & Fin Rot 
The tail & fins rots away. The edges are jagged like its been bitted by something. In serious cases, the fins and tail are torn or split opened. 
If the medication applied is effective, a black outline can be seen along the torn fins.
White spot 
Fish body is covered with white pepper-like specks. Very common when temperature drops. This is as common as our common cold. Keep your water temperature constant. 
Mouth Fungus 
White growth on the mouth. Much like wearing white lipstick but worse as cotton-like growth can sometimes be seen from the wound.
Fish Lice & Anchor Worms
(not a disease)
Usually they are introduced into the tank with live foods or plants. Although copper is the main ingredient used in treatment, you can also physically pulled them out with tweezers, and dap the wounds with "RID-ALL" Anti-Fungus.
Fungus
The white cotton-like growth is Not part of the fish fin. It is a secondary fungus infection normally due from injuries like fighting, or rough handling.
Pop Eye
Eyes swell out from its normal place and looks like it is about to pop out.
Swim Bladder Disease The fish either floats at the water surface or sinks to the bottom when not in motion. 
Dropsy  Abdominal area swells up and sometimes the scales protrude out. There is no known effective cure.
Hydra (pest)
This is a pest that may be introduced when you feed live foods. They are a danger to young frys only and post no threat to adult fishes. Click picture on the left for more information.

  To Previous Topic: Diagnosis
To Next Topic: Preventive Medicine