My opinion, the ammonia released from dechlorinator use is more harmful then the chlorine. For years I didn't dechlorintate unless doing a 50% or larger change with no problems. When they went to chloramines, I had to dechlorinate every time because they don't precipitate out of the water as quickly as straight chlorine. Then the ammonia released would burn their gills until I started using Prime, which binds to the ammonia to make it harmless until the bio filter can do its stuff. Anyone want a pound of dry sodium thiosulfate for free? Enough to dechlorinate a complete municipal water supply. Works great if you only have chlorine to deal with.