Question from Craig D. via email: Hi there, I have recently bought my daughter a small aquarium, to which we introduced a dozen Neon Tetras. In the 3 weeks my daughter has had the aquarium all of the fish have died. The latest culling was today after a water change. 6 fish died within a few hours of each other. The PH level has been fine but I suspect the chlorine level from the tap water is the culprit. Is there a precautionary treatment I should of done prior to adding the tap water? Great site, Craig. Hi Craig. Sorry to hear that you lost your Neons. It is quite possible that chlorine or chloramine is the culprit. There are products on the market that will neutralize chlorine and chloramine. I've had good results using AquaSafe. Another potential culprit, if your tank was not cycled, is ammonia. Check out the Nitrogen Cycle page for more information.