UNEXPLAINABLE DEATHS?!?!

[Dopatri]

Hi everyone.
I’m absolutely baffled as to what is going on with my fish. I have two tanks, one for guppies and one for guppy fry. I bought two new filters to put in my tanks yesterday, so I kept the original filters in the tanks, and just added the new filters as well. Anyway, I noticed a few hours afterwards all of my fish were acting strange, all gasping at the surface.

They were like this all night. Anyway, I woke up this morning and 4 of my guppy fry were dead, the rest have clamped fins and look close to death, and all the adults are still gasping at the top.
I’m so confused, all my water params are perfect, my tanks are fully cycled too. I don’t have bubblers in them but I make sure the filters cause enough disruption at the surface to make oxygen. There’s never seemed to have been a problem with oxygen since I started the tanks up 6 months ago so I don’t think it’s to do with that.
It all seems to be since I put the new filters in!!! I don’t understand, I even rinsed them in tank water before I submerged them in the tank. I’ve changed the water in both tanks now, and they’re still gasping at the top. I’m absolutely confused, had this happened to anyone else?
Thank you

 

[Colin_T]

they were poisoned by something, either something on the filters or on your hands. just do a big water change and gravel clean each day for a week to dilute any remaining poison in the tank.

 

[Bruce Leyland-Jones]

Hi everyone.
I’m absolutely baffled as to what is going on with my fish. I have two tanks, one for guppies and one for guppy fry. I bought two new filters to put in my tanks yesterday, so I kept the original filters in the tanks, and just added the new filters as well. Anyway, I noticed a few hours afterwards all of my fish were acting strange, all gasping at the surface.

They were like this all night. Anyway, I woke up this morning and 4 of my guppy fry were dead, the rest have clamped fins and look close to death, and all the adults are still gasping at the top.
I’m so confused, all my water params are perfect, my tanks are fully cycled too. I don’t have bubblers in them but I make sure the filters cause enough disruption at the surface to make oxygen. There’s never seemed to have been a problem with oxygen since I started the tanks up 6 months ago so I don’t think it’s to do with that.
It all seems to be since I put the new filters in!!! I don’t understand, I even rinsed them in tank water before I submerged them in the tank. I’ve changed the water in both tanks now, and they’re still gasping at the top. I’m absolutely confused, had this happened to anyone else?
Thank you

You sound as if you know what you're doing, so I can assume that not only did you prepare your new filters properly before putting them in the tank, but you also added the proper water conditioner to any water you added. I can also assume that you haven't added any contaminants, perhaps from your repeated hand-washing in these Covid-times?
Can I also assume that no contaminant has accidentally entered the tank from above?
What ARE your 'perfect' water parameters, including temperature?
Are you adding CO2?
Is your tank planted?

That aside, it definitely sounds like an oxygen problem and installing 'bubblers' can't do any harm.

 

[Dopatri]

they were poisoned by something, either something on the filters or on your hands. just do a bit water change and gravel clean each day for a week to dilute any remaining poison in the tank.

Oh no
I never thought of that. I did wonder at first though if it was something to do with the new sponges if there was some sort of chemical on them or something from when they were manufactured? But then I thought surely not. Who knows, maybe I did have something on my hands at the time but I didn’t realise. I’m just anxiously waiting now to see if they recover from this. I really hope so! Thanks for your reply.

 

[P J]

Hi, Have you been cleaning your existing filters excessively?
If so you may have compromised their efficacy, best leave them be unless clogged to a point that affects flow.

What type and brand are the new filters?

 

[Lajos_Detari]

Some additional questions.
This must be caused by some strong chemical or something in concentrated form.

Did anyone in your house spray some chemical near the tank?

Did you change the tank water recently and did you remember to use water conditioner (anti Chlorine)? Chlorine can kill your fish.

What filter brand and model that you bought?
If you suspected that it's caused by your new filters, then remove the new filters temporarily to see any improvement and to verify the root cause.