Oh Man

[malfunction]

I'm totally bummed out! I'm not sure what's happened, but my largest tank is self destructing. Every single fish in my tank is either dead or dying rapidly. It's frustrating me to no end as I have no idea what's causing it.

This all started on Tuesday. Summer is finally here, so the temperature has been fairly high lately. I noticed on Tuesday night that most of my fish were gasping for air and swimming near the outlet for my biggest filter. I assumed the oxygen level was low so fired up the air pump, and went to bed assuming the problem was solved.

Seems I was wrong. On Wednesday morning there were 3 dead geos - some of my favourite fish. I then decided to use my pond pump to introduce more flow. This pump moves 1000 l/h so provides more than enough disturbance for my tank. Still no help. When I got home from work there were more dead fish, and the survivors were struggling for air.

I tried a 50% water change, but still the body count keeps increasing. My ammonia and nitrites are testing at 0ppm; nitrates are 20ppm so I don't think this is a water quality issue. It can't be oxygen as with the two external filters and my pond pump, there should be enough oxygen for a tank considerably bigger than mine. There are no external signs of disease or injury on any of the fish. I'm completely baffled here. The problem seems to have appeared out of the blue. They all seemed fine until Tuesday. Anyone have any ideas what's causing the carnage?

 

[betta fish]

Sorry to hear this, what temperature is the tank reading at? could it be a heater issue perhaps?

 

[TwoTankAmin]

Please test for ammonia and nitrite to rule them out. Also, check the water temp. And have you added anything to the tank in the past month or two? There are a whole host of things that can attack the gills.

 

[Ch4rlie]

Sorry for your losses
 
But as the othres have asked good questions already, will await to see if we can work out some possibilities why this is occurring.
 
One other question, has your tap water changed in any of the parameters?
Might be an idea to test tap water, just for elimination processes.

 

[malfunction]

Sorry to hear this, what temperature is the tank reading at? could it be a heater issue perhaps?

I don't think it's the heater. The temp is reading at 26*C.

Please test for ammonia and nitrite to rule them out. Also, check the water temp. And have you added anything to the tank in the past month or two? There are a whole host of things that can attack the gills.

I added a royal whiptail catfish about 3 weeks ago. i didn't quarantine it as I didn't have any other tanks set up with enough algae. I'm starting to regret that now. If this were a disease, would it be able to kill so many fish within such a short time frame? Since Tuesday its been 9 geos, 2 lemon tetras, 4 denisonii, 4 rainbow cichlids and about 5 rainbowfish. And there were no signs of illness at all until Tuesday.

Sorry for your losses
 
But as the othres have asked good questions already, will await to see if we can work out some possibilities why this is occurring.
 
One other question, has your tap water changed in any of the parameters?
Might be an idea to test tap water, just for elimination processes.

I haven't tested my tap water for a few months, so I'm not sure if it's changed. I'll try it in the morning though. They started dying before my water change though, so I'm not sure if the tap water's the culprit.

 

[eaglesaquarium]

Did you add anything to the room recently?  We've had cases of things like air fresheners, etc. causing problems like this.

 

[TwoTankAmin]

Since you have fish dying and doing nothing may mean it doesn't stop, I am going to offer a suggestion I am not sure you can do in the UK. I would treat the tank for protozans. I would probably go broad and use two different meds. Over there maybe looks for the best ich med and then another antiparasitic that is not for ich or velvet.
 
Somebody from the UK can chime in. Over here I might mix praziquantel and Flubendazole or QuickCure (zinc free malachite green and formalin).

 

[ShinySideUp]

You say your largest tank, how big is it? Just after a bit more background info.

 

[RobRocksFishTank]

pH?
 
Anyone clean the outside of the tank recently?

 

[malfunction]

Did you add anything to the room recently?  We've had cases of things like air fresheners, etc. causing problems like this.

Nope - nothing has changed in my house. I'm always careful to avoid using aerosols in the same room as the tank.

Since you have fish dying and doing nothing may mean it doesn't stop, I am going to offer a suggestion I am not sure you can do in the UK. I would treat the tank for protozans. I would probably go broad and use two different meds. Over there maybe looks for the best ich med and then another antiparasitic that is not for ich or velvet.
 
Somebody from the UK can chime in. Over here I might mix praziquantel and Flubendazole or QuickCure (zinc free malachite green and formalin).

I'll give this a try - hopefully will calm things down.

You say your largest tank, how big is it? Just after a bit more background info.

8x2x2. It was my display tank where I kept my favourite fish.

pH?


 
Anyone clean the outside of the tank recently?

pH is 7.4. No one except me is allowed to clean the tank or use any chemicals or sprays anywhere near it. My brother takes on feeding duty when I'm away for work, but that's the only time anyone else is allowed within the exclusion zone.

 

[ShinySideUp]

Clutching at straws now: Do you have large snails and if so can you account for them all? Is the whiptail still alive and thriving?

 

[malfunction]

Well whatever caused the catastrophe seems to be easing up by itself. No dead fish today, and the survivors seem more normal. There are a few that seem lethargic, so I anticipate there'll be a few more deaths in the next few days. This is really annoying though, as I just can't pinpoint the cause of all this.

Clutching at straws now: Do you have large snails and if so can you account for them all? Is the whiptail still alive and thriving?

No snails in this tank - my rainbow cichlids make sure of that. The whiptail is missing at the moment. I'm presuming he was one of the fatalities.

 

[malfunction]

Things have definitely stabilised now as there've been no more deaths and everyone's acting normally. It's really irritating not getting to the bottom of this, but thanks to all those who tried to help.

 

[RobRocksFishTank]

No one has mentioned a noxious gas release. Not even sure how you could verify this.

 

[malfunction]

No one has mentioned a noxious gas release. Not even sure how you could verify this.

You mean like hydrogen sulphide? Could be I suppose. Wouldn't it kill instantly though! Instead of over several days?