Our water definitely has chloramines, so I wonder if the amount is just so small that it isn't harmful to the fish?

http://www.sandiego.gov/water/quality/t ... cess.shtml
Chlorine is added to the water as the primary disinfectant to prevent illness due to water-borne pathogens. The final barrier is the addition of ammonia to the water to react with chlorine and form chloramines. Cloramines are used to maintain a residual disinfectant throughout the water distribution system to ensure water quality to the consumer’s tap.