Fish dying after adding new lid?

[SidneyE]

Hoping someone can give me an idea what could be going wrong…

65g tank setup since January, seeded with a sponge filter from an established tank. All inhabitants doing well, mostly pea puffers, a few danios, otos, one hillstream loach. Up until this weekend had an egg crate light diffuser for the top. Saturday made a top out of lexan polycarbonate. Glued hinges on using regular super glue. Water parameters stay stable, no ammonia or nitrite, nitrate around 20ppm. Sunday morning wake up to dead danio. Tested water, all good. Later in the day do weekly water change and discover dead hillstream loach. After water change find dead pea puffer. Monday morning another dead pea. The remaining puffers seem fine. The remaining two danios are breathing heavy so moved to a different tank on Sunday. After Sunday water change added second air stone and propped open new lid thinking maybe it was an oxygen issue? Other equipment in tank: HOB, sponge filter, heater.  
No other signs of disease on fish. All have been wormed, peas are fat and happy. Could the new lid have anything to do with the loss or is this just a coincidence? 

[Guppysnail]

Adding a lid can significantly increase temperature which consequently reduces oxygen. Most source water comes in oxygen depleted so further reduces oxygen.  Have you checked your current temperature against what it was previously? 

[SidneyE]

Thanks for the input! Yes, it went up about 2° when I added the lid. I have the heater on a thermostat, it’s set to 76° and Sunday afternoon it was 77°. Prior to the lid it was usually around 75.5°. 
That’s what I was worried about and why I added the second air stone Sunday afternoon. 

[Wrencher_Scott]

On 5/16/2022 at 8:56 AM, SidneyE said:

Hoping someone can give me an idea what could be going wrong…

65g tank setup since January, seeded with a sponge filter from an established tank. All inhabitants doing well, mostly pea puffers, a few danios, otos, one hillstream loach. Up until this weekend had an egg crate light diffuser for the top. Saturday made a top out of lexan polycarbonate. Glued hinges on using regular super glue. Water parameters stay stable, no ammonia or nitrite, nitrate around 20ppm. Sunday morning wake up to dead danio. Tested water, all good. Later in the day do weekly water change and discover dead hillstream loach. After water change find dead pea puffer. Monday morning another dead pea. The remaining puffers seem fine. The remaining two danios are breathing heavy so moved to a different tank on Sunday. After Sunday water change added second air stone and propped open new lid thinking maybe it was an oxygen issue? Other equipment in tank: HOB, sponge filter, heater.  
No other signs of disease on fish. All have been wormed, peas are fat and happy. Could the new lid have anything to do with the loss or is this just a coincidence? 

I would suspect chlorine in the water if you use a city water supply. They can and will chlorinate high at times. It's good to test after you dechlore or at least dose dechlore 4 times or so if the bottle says it's ok. 

The only other suspect would be the glue if it wasn't cured all the way.

Say it was oxygen, it seems like they would head for the top for air. But lots or aeration is always good, it of course would be best to add lots just in case. 

My money is on chlorine. The tell is water changes. 

Anyway, just my 2 cents, good luck. 

 

Edited May 16, 2022 by Wrencher_Scott

[SidneyE]

Sorry if it’s not clear 2 of the 4 fish started dying before water change. Last water change was over a week ago. I do wonder if the glue had anything to do with it…

[Jenja]

Could definitely just be the temp increase and subsequent oxygen drop, and super glue is known to be safe even in water, so I'm wondering if there's some kind of contaminant on the polycarbonate. Did you rinse or wipe it down before adding it? Perhaps you unknowingly got something on it when you were cutting it to size.

[Brian]

I can’t help but think just maybe the first fish died from an unrelated cause.  And maybe the water change had something to do with the others.  
The material used for the lid you made should be safe.  I can only guess that a lot of DIY’ers have done the same.  But we don’t know if the materials used could have been contaminated while in shipping or sitting on the shelf.  
 

[Colu]

Did you use a cyanoacrylate based glue 

[SidneyE]

Yes, but I’ve read that cyanoacrylate glue is aquarium safe? 

[Colu]

On 5/17/2022 at 12:26 AM, SidneyE said:

Yes, but I’ve read that cyanoacrylate glue is aquarium safe?

 it is I was just asking in case you used a different type of glue

Edited May 17, 2022 by Colu

[Guppysnail]

On 5/16/2022 at 7:26 PM, SidneyE said:

Yes, but I’ve read that cyanoacrylate glue is aquarium safe? 

It is. @Odd Duck actually glue underwater in the tank. 

[Odd Duck]

Yes, I’ve glued underwater many, many times with no apparent adverse effect and fish, shrimp, and snails nearby acting like nothing is wrong.  Not to mention the many times I’ve placed freshly glued pieces in the water immediately or very soon after gluing.

My guess would be a difference in oxygenation for a potentially already sick fish that then set off a chain of adverse events?  Possibly a little interaction with a heavy chlorine shock by the water company for following deaths?  Pretty much guesses without having any indications from water parameter results or any other obvious suspects.

Sorry for your losses.

[Torrey]

On 5/16/2022 at 5:26 PM, SidneyE said:

Yes, but I’ve read that cyanoacrylate glue is aquarium safe? 

Perfectly safe, and humidity speeds curing. I glue and put straight in the aquarium, and not even shrimp are bothered.

Most likely the slightest temp increase ==> decreased oxygen saturation ==> increased stress ==> initial deaths in "lower school position" fish (lower social hierarchy generally correlates with increased stress/less resilience) ==> added minor spikes in ammonia ==> more deaths

Without information like [average] water parameters before the lid, and testing after first death and after water changes, hard to be more specific.

Most likely scenario is low oxygen plus stress.

A plausible scenario is a contaminant on the lid. Not likely, but still plausible. 

[nabokovfan87]

I am thinking....

PH, Temp, and Oxygenation all played a part in this one.

Initially I would think there may have been a chemical or oil from the surface of the glass, a cleaner, something that caused issues. The fish are scaleless, which means something like that would cause these kinds of issues.

Take the lid off, clean it really well, check the water surface for film and if you see some I'd likely change a large volume of water.

Edited May 17, 2022 by nabokovfan87

[SidneyE]

Thanks everyone for your thoughts. I dose double Prime during water changes. Yes, city tap does read slight green when I test for ammonia, it has since day one. 

I suspect that temp change/oxygen levels/stress is the culprit. The fish also seem a little stressed from the new lid, I guess to them it’s a big change to their environment. Last night I fed daphnia and hunting seemed to set the Peas right, no more hiding in the back. 

Haven’t had anymore losses since the four and the danios I moved to another tank are no longer breathing heavy and back to normal. This is my first large tank, lesson learned. Now I’ve got air stones on both ends of tank. 

[Guppysnail]

I’m glad everything is settling down for you.  Every new venture in this hobby has a learning curve even if you have been keeping fish for awhile.  

[Wrencher_Scott]

On 5/17/2022 at 4:38 AM, SidneyE said:

Thanks everyone for your thoughts. I dose double Prime during water changes. Yes, city tap does read slight green when I test for ammonia, it has since day one. 

I suspect that temp change/oxygen levels/stress is the culprit. The fish also seem a little stressed from the new lid, I guess to them it’s a big change to their environment. Last night I fed daphnia and hunting seemed to set the Peas right, no more hiding in the back. 

Haven’t had anymore losses since the four and the danios I moved to another tank are no longer breathing heavy and back to normal. This is my first large tank, lesson learned. Now I’ve got air stones on both ends of tank. 

Oh, I think I missed that. Did they hang out on the top too? That would be aeration. Like mentioned before it could be they were kind of on the edge when whatever happened to do them in. 

As for glue, I use super glue to glue plants to rocks but I always soke them in water for a few minutes before I put it in the tank. Better safe than sorry. Actually I rinse everything that goes in very well. I see it like poisons in the water that won't dissipate for who knows how long... I don't want my fish in that. 

A little ammonia is not deadly over night, it poisons the fish but it take a long time and a good filter with lots of bio media will take care of it quick.

I think the best defense to any problems is a large filter filled with course foam like 20 or 30 ppi. No one ever asks or mentions anything about filtering or cleaning it when they have problems. Don't clean filter media just rinse it. I like pointing to this video by Cory, all about the need for lots of filter media. This works on canisters too, not just HOBs. Search Youtube for optimizing HOB filters by aquarium coop. 

Foam is MUCH better than any of those bio balls or Matrix rocks. The secret is the surface area for the BB to grow and live on. A great filter makes all the difference in making fish keeping easy. Course foam is a piece of cake to rinse out (in tank water) and it doesn't need to be done very often, like months at a time. It makes all the difference in your water quality. 

Edited May 18, 2022 by Wrencher_Scott

[Brandon p]

When you add a lid a lid there is a lot of surface area where there is no gas exchange. I think you did well add an air stone. I have some openings where air tubing and the heater go. I also added a small wave maker. I think it’s for a 10gal and it’s in a 75g. I have near the top jus to help with mixing the air that gets in.