Real Emergency, Immediate Help Required

[doresy]

My son-in-laws Malawi set up is in trouble

History,

Mature tank, ocean rock, a dozen or so mixed malawis (some large)

He removed all the rock, put it in buckets and left in the room next to the tank. They were out for a few days to stop the fish gaining territories as he was getting new fish.

Yesterday he got 4 large malawis and introduced the into the tank. Also replaced rocks. This morning one of the new fish was dead. Tonight, most of all the fish are at the top of the tank pushing their heads out of the water.

He called me in a panic! I got him to test the water for ammonia (zero) nitrite (zero) Nitrate (40 ppm) so all good there.

I thought maybe something on the rocks had died off and as he didn't rinse them off maybe acidic? Ph test showed around 8.

The next thing I thought was maybe poisoning (maybe something got on the rocks while out of the tank) so he is, at present, doing a massive water change.

The new fish came from a pristine tank and experienced keeper so probably not disease or the like.


Have we missed anything?

 

[moochy13]

i always thought fish collecting at the top means temperature/oxygen problems. though i cant see why this might have changed. hopefully if anythign is contaminated a big water change each day for a few days will suffice.

 

[AstonN24vantage]

nitrates are 40? isnt that too high? has he done a WC yet?

 

[Tolak]

Large water change, nitrates of 40 are of no real concern.

 

[AstonN24vantage]

ok. i always get a bit nervous with my angels if they get above 20 tho

 

[doresy]

i always thought fish collecting at the top means temperature/oxygen problems. though i cant see why this might have changed. hopefully if anythign is contaminated a big water change each day for a few days will suffice.

Temp is at usual level and no reason to suspect lack of oxygen as good surface agitation and last water change just before fish and rocks went in.

We all have 40 ppm out of the tap here which has never presented a problem before

He is in the process of a midnight water change as we speak!

I'm still with contamination of some kind in which case the massive water change should improve the situation. I just hope he hasn't got a tank full of dead fish in the morning

 

[kiriyama]

Maybe some kind of bacteria forming on the rocks when out of the water ? I'm only taking a stab in the dark though ?
I'm wondering how much (if any ?) the pH would have dropped when rocks out and raised again when back in but I can't see that causing this ?
Really sorry mate , I'm baffled, the gasing is usually as previously mentioned temp or oxygen problem..
How deep is the substrate ? What type of substrate ? Was it disturbed or stirred up during the change ? Any smells from the tank ?

 

[doresy]

Maybe some kind of bacteria forming on the rocks when out of the water ? I'm only taking a stab in the dark though ?
I'm wondering how much (if any ?) the pH would have dropped when rocks out and raised again when back in but I can't see that causing this ?
Really sorry mate , I'm baffled, the gasing is usually as previously mentioned temp or oxygen problem..
How deep is the substrate ? What type of substrate ? Was it disturbed or stirred up during the change ? Any smells from the tank ?

Black gravel and no to all the rest. I only thought ph incase acidic bacteria formed while out of the water.

Oh well, bed time now....time will tell

 

[kiriyama]

Hope you get it sorted mate...