Tetras dying after introducing new filter

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Aquariophile

Aquarium Advice Newbie
Joined
May 23, 2018
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I have a 55g aquarium cycled for about two years. I was using 2 Fluval C4 hob filters, and I had frequent issues with one of them, so decided to get a canister filter. I got the Penn Plax 1200.

I installed the Penn Plax last Friday. I decided to keep using one of the C4 for the time being, and I took the biomedia (Matrix) I had in the other C4 and in a box filter that I kept in the aquarium if I needed to start a quarantine, that I placed in the Penn Plax with a lot more of new Matrix for the top tray (I also have Purigen there). I also have 2 trays full of new Biohome (another biomedia that I'm using for the first time). The bottom tray is sponge and floss. I probably have close to 10x more biomedia than before, albeit most of it is not cycled. But I didn't take any cycled biomedia out of my previous setup. I also added Seachem Stability to help colonizing the new media.

So everything was fine until yesterday (Tuesday). In the morning, I noticed that 3 ember tetras and 1 lemon tetras were dead. I had to go to work, but measured ammonia which was at 0. When I came back from work, 5 more embers were dead. I tested: ammonia 0, nitrite 0, nitrate 20, ph 7.2. Not knowing what to do, I did a 50% water change and added more Seachem Stability. I also decided to run carbon (which I've never done) in case there was some toxicity in my water that I could not detect.

I also turned off the air stone I had and lowered the flow on the Penn Plax (and moved the direction of the diffuser), since the only other change I could see is that I have more water circulation than before, and I'm wondering if they died of exhaustion.

This morning: my remaining 3 embers and 4 lemons dead. Coming from work: 1 lemon and 2 glowlight tetras dead. So I decided to further slow the water flow.

I tested again tonight: ammonia 0, nitrite 0, nitrate 10.

My aquarium was well stocked: about 105% according to aqadvisor. I have corys, platys, neon tetras, gold tetras, glowlights, endlers, danios, and now 1 remaining lemon tetra. I never had any issue in the last 2 years.

All my fish appear fine. That said, I'm now also worrying about oxygen, since I don't know if I have enough water circulation.

Any idea what's the problem and what I should do? Sorry for the long post, thanks for reading.
 
Primary parameters looks good, Good call on the carbon too.


If it was O2 level you would notice them gasping at the surface, are they at all? How is your surface agitation?
 
Primary parameters looks good, Good call on the carbon too.


If it was O2 level you would notice them gasping at the surface, are they at all? How is your surface agitation?
^^^+1^^^

Good call on quick carbon …Change it out if possible in a couple days ..It really won't last long if it is doing anything..
This is the time of year water suppliers are flushing the systems and upping the amount of chlorine and chloramine in your water supply...
Did the fish look at all distressed or show any symptoms?

Not having a heater issue are you ?
 
Well, lost another glowlight during dinner.

No one is gasping. I do have some agitation, but it's much less than it was when I had 2 power filters, one air stone and one corner filter.

All fish seem fine, even the glowlight that just died didn't appear to have any problem a few hours ago. That's in part what's puzzling to me. I could see yesterday that the few surviving embers were hiding, but other than that, nothing different. The lemon tetras were more peaceful than usual, but the color was fine and they were not hiding. But they are the reason I wonder if they were not exhausted by excessive water flow.

I should have mentioned it in my original post, but I did double-check the temperature by using a second thermometer, and no issue there.

I'm thinking of adding more carbon since you're both telling me it's a good call. I was also thinking of doing another big water change, but I'm now wondering if the tap water is my problem.
 
I would test the tap water, You could be adding a lot of ammonia if you have it in the tap water.


What is all in the new filter?
 
Update: no more death in the last 20 hours. All the fish look fine, although the only surviving member of my group of 12 ember tetras is hiding, which I guess is not surprising since it's a schooling fish, but it gets out to feed. Yesterday it was hiding so well I didn't know it was still alive

The sole surviving lemon tetra (I had 8) is also looking fine, as well as my 4 surviving glowlight tetras (one wasn't looking good early this morning, but now is ok).

My other fish: 6 corys, 4 leopard danios, 9 platys (2 are babies), 12 neon tetras, 3 otocinclus, 5 gold tetras. All of them look in good shape.

So I'm left with two theories as to what happened:
1. Something toxic got into my water, via the new canister filter or otherwise; or
2. I had too much water movement and they died of exhaustion.

I decided to add an airstone 2 hours ago, I didn't like the very limited agitation on the surface. I saw that although none was gasping, all the fish, in particular the neons, were staying higher than usual in the aquarium; they're now all back to their regular level. Also, I like the bubbles!

So hopefully all will be good now. I feel bad for the lemon and ember being alone, but I won't add any fish before at least 2 weeks, more likely a month.
 
Although it does seem very coincidental with timing it is possible the embers and lemons are just reaching the end of their life .Although some say "up to 10 years" most average out at 2-4 years with many being wild caught and not even of known age when sold..Many believe embers are 1-2 years old when offered for sale …
Good luck and just stay on top of water quality...
 
I thought about that when I had the first deaths, but I have a hard time believing now that 7 of 8 lemons would reach end of life within the same 36 hours period, along with 11 embers and 2 glowlights.

But I guess I will never know for sure what happened.
 
So, you didn't add any bio media out of your previous set up? Have you tested your tap water for nitrate at all? Are you pretty much cycling the canister filter? The nitrate could be showing up because of your tap water and you could be having spikes. (like you would while cycling a new tank) I'd test the tap for nitrate and start testing the tank at different times than you are. Hopefully, it's under control now. But, you never know.
 
I didn't take any bio media out, but I added about 8-10x more than I had before. I had 2 hob filters; I kept one intact (except for adding carbon later on) and it's still running, and took the bio media of the other one and the bio media of a box filter and placed it all in the new canister (with the new bio media).
 
Update: I lost one gold tetra yesterday, but I'm leaning toward thinking that it was just old. I lost a first gold tetra about 2 months ago (at that time only second fish I had lost in 18 months), and I got them 2 years ago.

So, having more time on this Saturday morning, did a bunch of tests:

Aquarium water: Ammonia 0, Nitrite 0, Nitrate 30, PH 7.2, Phosphate 0.25
Tap water: Ammonia 0, Nitrite 0, Nitrate 0, PH 7.2

Nitrate is surprisingly high in the aquarium, since I usually get to that level only if I'm at least 2 weeks without water change (it's been 3 days since a 50% water change). Still it's an acceptable level, but I believe it shows there was some bacterial activities and cycling going on (maybe I still had 0 ammonia and nitrite because of Purigen?)

For ammonia, since I had a 0 reading a few days ago but I was expecting some trace in tap water because of chloramine, I tested both aquarium and tap at the very same time to compare colors. They were both identical, very much yellow (API test). I could not tell them apart.

I also tested nitrate in tap twice, since I was surprised to have a reading at 0. But there's really no doubt (again very yellow).

I will now do a small water change, and hopefully everything will be fine going forward.

I'm coming to the conclusion that I had too much water circulation and some species (lemon and ember) could not survive. In fact, looking at how my fish behave now, I'm thinking that I've always had too much water circulation, it just wasn't at a deadly level before. For example, my neons and my glowlights are swimming a lot more at different levels instead of remaining in the bottom third. The danios were always midway in the middle and the top, and are now a lot more at the top.

I was probably a bit too obsess by oxygen in my water, as shown by some of my posts. So hopefully, I will have learned a lesson out of all that happened and I will be able to provide for a better environment for my fish in the future.

Thank you to everyone who answered my posts.

I always welcome comments and suggestions, but I'm also providing this update for the benefit of anyone reviewing this thread and faced with a similar problem.
 
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