Goldfish
The goldfish ("Carassius auratus") is a freshwater fish in the family Cyprinidae of order Cypriniformes. It is one of the most commonly kept aquarium fish.
Common goldfish
"Fin Rot" is developed from bacteria eating/ deteriorating the fins of the goldfish. The disease starts from “poor water quality, overcrowding, sudden temperature changes, fin nipping, or aggressive fish”; this will lead to torn and shredded fins that could possibly deteriorate the body tissue to prevent the regrowth of their fins. Fin rot is known to be treated early to prevent further damage to the body tissue to the fish so the disease does not spread. Treatments start with clean water, adding aquarium salt to clean the water; if the following does not work then commercial products should be used along with weekly water changes.