Tank Problem

[Sasha]

OMG, I don't know what's going on with my 29 gallon. The tank is stocked with guppies, platies, a molly, pristella tetras and one lonely neon tetra. Yesterday, I found 8 fish dead!! I immediately tested the water and everything was perfect.

Ammonia -0
Nitrate - 0
Nitrite - 0
pH - 6.8

They showed no signs of disease prior to their death. I do a 25% water change every week and have done nothing out of the ordinary. Last night, I did a 50% water change, since I didn't know what else to do. The only new fish that I added were some baby mollies last week that I got free from the LPS, but they seem heathy. I moved them to a seperate tank last night. Could they have carried some sort of disease into the tank?

This morning, I found 6 more dead fish!

 

[Clairel]

OMG im so sorry

I also got 6 baby Mollies free from the shop....(strange) Lol

I had some problems with my ammonia and lost a Gourami and a Shark, but other than that, i dont know what to suggest your stats appear fine...Same as mine actually, apart from my PH is 7

I hope you find out what it is, is your Filter ok? Any new pads?

Claire x

 

[MarkOne]

You should be seeing some nitrates...how long has the tank been running? Was it mature before you added all these fish?

 

[Sasha]

is your Filter ok? Any new pads?

Yes, my filter is ok. I replaced the carbon last night.

how long has the tank been running?

The tank has been running for 3 years. Last year, I had a similar problem with the same tank. I lost over half of my fish for no reason. So, I moved them into my 46 gallon and cycled the tank again.

Was it mature before you added all these fish?

All of the fish in the tank are fish that I raised from fry. So, they've been in the tank their entire lives.

 

[The-Wolf]

Hi Sasha, good to see you around,
but sorry it's under these circumstances.

ok
the sudden death of many fish, with little or no preceding symptoms
could be poisoning of some kind (soap, lead, etc.)
I doubt it very much in this case.

it could be low oxygen levels.
is there any surface agitation, is it enough?
you could add an airstone to increase the surface agitation, thus promoting a better O2 exchange at the surface.

it could also be, and I'm leaning towards this one
Peracute bacterial disease.

I would, as you have, perform a large water change, and continue to do so for the next 3 days. In the meantime I'd add melafix (and if to hand pimafix) to combat any baterial problems there maybe. I say melafix because it's natural and it won't hurt if it is not PBD.
The large water changes for the next few days will combat the poisoning if indeed that is the cause.

HTH
and good luck

 

[Sasha]

is there any surface agitation, is it enough?
you could add an airstone to increase the surface agitation, thus promoting a better O2 exchange at the surface.

Well, the tank has an Aquaclear 200. None of the fish seem to be gasping for air, but I can add an air pump into the tank just in case.

it could also be, and I'm leaning towards this one
Peracute bacterial disease.

I would, as you have, perform a large water change, and continue to do so for the next 3 days. In the meantime I'd add melafix (and if to hand pimafix) to combat any baterial problems there maybe. I say melafix because it's natural and it won't hurt if it is not PBD.
The large water changes for the next few days will combat the poisoning if indeed that is the cause.

Ok, I just added some Melafix into the tank and I'll continue to do water changes.