Background

This bacterial goldfish disease is common and can affect all type of Goldfish and other freshwater aquarium fish. Goldfish can be stressed, which can cause the bacterial disease, for many reasons including but not limited to;

• rough handling
• fighting
• overcrowding
• poor water quality
• incorrect water quality
• very low temperatures (below 50F) 

Diagnose

Symptoms can include; 

• Split and/or ragged fins, often with a white edge to them
• red streaks in fins. 

If left untreated, fins gradually deteriorate until they are completely gone and disease then infects the goldfish's body.

Treatment

A hospital tank is the best place for an affected goldfish. While a 0.3% salt solution may cure mild cases, a broad spectrum antibiotic, or antibacterial medication should be used. Antibiotic medications can affect the cycle so monitoring water quality during treatment is recommended. As with most bacterias, perfect water quality is essential for the fish to recover.  

Prevention of finrot is easy and includes common care tips for Goldfish.

• maintaining good water quality
• correct stocking levels
• not keeping 'nippy' fish with goldfish.