Ammonia poisoning is one of the biggest killers of aquarium fish. Ammonia irritates the fish by burning their gills and scales.  Sometimes the scales even fall off.  It occurs most often when a tank is newly set up. However, it can also occur in an established tank when too many new fish have been added at one time, when the filter fails due to power or mechanical failure, or if bacterial colonies die off due to the use of medications or sudden change in water conditions.

Symptoms:

• Fish gasp for breath at the water surface
• Purple or red gills
• Fish is lethargic
• Fins are torn & jagged
• Loss of appetite
• Fish lays at the bottom of the tank
• Fish may appear darker in color
• Red streaking on the fins or body