Fish deaths immediately following water change

[Brhino]

Did a water change on my clown loach tank just now. Came back 45 minutes later to feed them and 2 of my 8 loaches are stone dead. No signs of distress whatsoever from the survivors, nor from the dozens of danios and the pleco in that tank. Water parameters check out just fine, 0/0/15.

I'm pretty crushed. What did I do? Did I forget to add prime (I have since added a double dose just in case)? I can't say with complete confidence that I remembered. You would think other fish would be showing signs of distress... or that there would be an ammonia reading. Temperature variance? I was keeping an eye on that as I refilled the tank... and if there was one, the heaters got it back up within that 45 minute window. What else could I have done?

Really upset. These fish grow so slowly, I've had them for a year and I was just admiring the size they put on... and now I just killed two of them somehow.

[Rocksor]

test your tap water, maybe they increased the chloramine level.

[Brhino]

I don't have anything to directly test for chlorine/chloramine... would that show up as ammonia, or not?

[William]

Sorry for your loss.

It would not. Clownloaches can be very sensative to chlorine. Compared to the rest of your fish they are sensetive to everything.

[Allesgut]

Brhino, could you please describe the % of the water change and frequency you used to follow?

[Brhino]

50% weekly.

[CrazedMichael]

Hmm, very unlucky. Clown loaches are beautiful fish.

Hope you get to the root of the problem. Like others have said, it sounds like poisoning of some sort. maybe the water you added had a high amount of ammonia at the time, which would have cleared up within 45mins thanks to the filters.

[Lady Hobbs]

Oh Brhino......I am so sorry. No wonder you are upset. On the chance you did forget the Prime, you will have to watch that your filters did not lose the bacteria in that time, as well. I don't think it would take much chlorine to do so. Really sorry.

[Lady10Godiva]

That sucks man. I dont really know anything else it could be.

[funkman262]

Is it possible that they were already dead before the water change but you didn't notice until afterwards?