Dead In 24 Hours?

[overboard]

Just wondering what might have caused this.

I have a 30g planted tank. With a homemade C02 injector.

Had 4 platies and 3 kuli loaches for at least a year.
Added 2 new platies and an angelfish.
All seemed well until the next night when 3 of the 4 original platies
are found dead. The angle fish won't eat and is now missing and I'm
left with the 2 new platies and 1 original and all seem timid and
seem to hide unless I put food in.
What could have done this in 1 night? There's at least 1 or 2 of the loaches left.

Water looks clean and clear and no visible signs of disease like ick.

Stress maybe?

What should I do or test for?

 

[OldMan47]

Try a test for ammonia or nitrites. Chances are you will not find anything there. That leaves us to figure out what may have changed in your tank. My first guess is that you do not do water changes very often and decided that the new fish needed decent water in their new home. That might have prompted you to do a large water change on an old tank that had not had much attention. If this is what really happened, the problem could be from what is called Old tank syndrome.

 

[The-Wolf]

that many deaths in such a short time after the introduction of new fish ...
I'm thinking systemic bacterial infection

 

[Harlequins]

I agree with oldman,test your water first,good luck

 

[hughessomefish]

good luck that must stink but yes do a water check.

 

[Squid]

that many deaths in such a short time after the introduction of new fish ...
I'm thinking systemic bacterial infection

There's an old name.. Just come back myself, you not around here much these days?

 

[overboard]

I read a bit on old tank syndrome, doesn't sound like what happened. I didn't do a water change when I put the new fish in and I didn't put any water from the pet store bags in the aquarium.

I just did a Ammonia test. The levels were very slight. Somewhere between 0 and 0.25mg/l. So I just did a 25% water change and put a couple of tabs of tank safe in to remove chlorine etc. Going to test the ammonia in a few hours again.

So the 2 new platys are still alive and one of the old as well. The angelfish is nowhere to be found. At least 1 kuli loach left. The fish that are left seem ok. We will see what happens.

 

[VaegaVic]

Just wondering what might have caused this.

I have a 30g planted tank. With a homemade C02 injector.


Stress maybe?

What should I do or test for?

Did you by any chance move the injector when putting the new fish in? Turn the filter off or squeeze in the injector?
Squeezing the injector how ever so slightly can cause a feedback, possibly pumping yeast and ethanol straight into your tank.

Might be an idea? As ethanol (produced by yeast) looks exactly like water.

 

[overboard]

That sounds like it might be a possibility. I did change that recently. Is it strange that all the fish didn't die?

 

[VaegaVic]

That sounds like it might be a possibility. I did change that recently. Is it strange that all the fish didn't die?

Not in the slightest, some could be more resistant, others could just be weaker.