Even if your town has used chlorine in the past, if they switched to choramine it could cause an unexpected problem. When my town changed I knew ahead of time and got chloramine/ammonia remover. But I think they were unsure of just how much would be enough and put extra (just speculation). I treated the new water per instructions but a couple of fish I had kept for at least a dozen years died, both within a week. It just seemed to be a little too much of a coincidence.
With your fish there are just too many possible causes. But having enjoyed much DPW tinkering with various water supplies I have become distrustful of municipal water supplies.
If you can locate unheated tanks/bowls in warmer locations the fish will also probably have better immunity to problems. Even a higher shelf might add a degree or two.
An advantage, other than water quality, of doing daily water changes is that the water the fish is in doesn't have chance to have a big pH change which will happen with a build up of waste.
violet
|