What killed my fish?

jrlafrance · Dec 30, 2017

So I had a bio-pellet reactor running in my tank, but for the last couple of weeks had turned it off (don't remember why). One day, my OCD kicked in when I saw something unplugged, and plugged it in. Almost immediately I smelled the "rotten egg" smell and unplugged the reactor. Unfortunately the damage had already been done. The fish started swimming all crazy, and even though I put them in a small 5 gallon tank, one by one they died.

So, I have a couple of questions. What killed my fish ( other than my stupidity), and secondly, if its hydrogen sulfide (H2S) like I've read about, how do I get it out of my tank? I've torn the tank down, cleaned with vinegar, emptied the sand that was in the sump and cleaned the sump as well with vinegar. Both are currently drying. Will this be enough to put fish in again?

DLHDesign · Dec 30, 2017

I'm sorry for your loss. It's never easy. :-(

Sounds like it could have been hydrogen sulfide poisoning, perhaps - certainly your nose told you it was present if you could smell it, and potentially (likely) in enough of a concentration to kill. It's also possible that some detritus build-up decayed into ammonia, being introduced back to your tank when the flow resumed. It could have been either, both, or something else entirely...

H2S will oxidize when in contact with oxygen (such as from the air), so I doubt much extra effort need be made. You can ensure that the equipment is in a well lit area if you want to speed it along. If you really wanted to ensure it's all gone, soak everything (or as much as you can) in some aerated water (again; oxidation) and run some GFO with it (and/or carbon - both if you can, but GFO more-so).

Here's an article that may help; specifically the last section (which I'm basically trying to paraphrase above).

Randy Holmes-Farley · Dec 30, 2017

Yes, it is likely hydrogen sulfide killed them, and I think what you have done is plenty adequate. The GFO is also a good way to make sure if there is any seeping from pores in your rock, that it won't reach problematic levels, but that isn't all that likely anyway.

jrlafrance · Jan 1, 2018

Thanks for the reply Randy! I cleaned the tank and sump with water and vinegar, I cleaned the equipment (pumps and plumbing) with water and a brush, then let it dry out completely. I filled the tank again, installed a small UV, put in some carbon, let it get to temperature and tested the water. Ammonia, nitrites, nitrates and pH all tested good, as well as salinity. I purchased 1 green Chromis and acclimated it for 3 hours. Put it in the tank, and after 12 hours I had to take it out and put it in a different tank because it had started to behave similar to the other fish that died. After another 3 hours of acclimation, the fish is good in the other tank. I'm disturbed because I don' know what could be the issue with my tank still. Do you have any opinions? The tank is still running, I was gonna let it do its thing for awhile. Since I can't test for H2S, I'm not sure what else to do.

Randy Holmes-Farley · Jan 1, 2018

jrlafrance said:
Thanks for the reply Randy! I cleaned the tank and sump with water and vinegar, I cleaned the equipment (pumps and plumbing) with water and a brush, then let it dry out completely. I filled the tank again, installed a small UV, put in some carbon, let it get to temperature and tested the water. Ammonia, nitrites, nitrates and pH all tested good, as well as salinity. I purchased 1 green Chromis and acclimated it for 3 hours. Put it in the tank, and after 12 hours I had to take it out and put it in a different tank because it had started to behave similar to the other fish that died. After another 3 hours of acclimation, the fish is good in the other tank. I'm disturbed because I don' know what could be the issue with my tank still. Do you have any opinions? The tank is still running, I was gonna let it do its thing for awhile. Since I can't test for H2S, I'm not sure what else to do.

Any GFO in the tank?

Any smell?

I suspect it may be something else now (maybe before).

jrlafrance · Jan 1, 2018

I just out some GFO in a reactor this morning. I don' smell anything odd. I'l let it go for a few days and test with another chromis. Thanks for the help Randy!

Randy Holmes-Farley · Jan 2, 2018

You're welcome.

Good luck!

jrlafrance · Jan 4, 2018

OK, a few more details to help diagnose. Tank is a 22 gallon bowfronts with a 5 gallon sump. I ran the GFO for 2 days and acclimated another chromis. After a couple of hours it started to have same reaction as the other, erratic swimming then sinking to the bottom and laying on its side. I transferred it to another tank and acclimated it again and saved its life! Anyways, I'm still running the GFO, but unclear as the way forward. Is there anything I can put I to the tank to help "clean" it? More vinegar? Is it possible the silicone is leeching?

Randy Holmes-Farley · Jan 4, 2018

jrlafrance said:
OK, a few more details to help diagnose. Tank is a 22 gallon bowfronts with a 5 gallon sump. I ran the GFO for 2 days and acclimated another chromis. After a couple of hours it started to have same reaction as the other, erratic swimming then sinking to the bottom and laying on its side. I transferred it to another tank and acclimated it again and saved its life! Anyways, I'm still running the GFO, but unclear as the way forward. Is there anything I can put I to the tank to help "clean" it? More vinegar? Is it possible the silicone is leeching?

The substrate was removed?

Cnidoblast · Jan 4, 2018

Interesting fact: H-S-H numbs your nose after a while and you stop smelling it

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2850187/

"At the beginning of the welding process, white fumes with a “rotten egg” odor emanating from the container. The patient immediately felt dizzy and developed rhinorrhea, teary eyes, nausea, and shortness of breath, chest tightness and cough."

jrlafrance · Jan 4, 2018

Randy Holmes-Farley said:
The substrate was removed?

Yes, all the substrate and the rock has been removed. Just occurred to me, the only things not cleaned is the pump for the GFO (was originally used for the bio reactor) and the PVC used on the tank as hiding places for the fish. However, it has been several days now with the lights on during the day, sump light at night as well as the UV.

Randy Holmes-Farley · Jan 5, 2018

jrlafrance said:
Yes, all the substrate and the rock has been removed. Just occurred to me, the only things not cleaned is the pump for the GFO (was originally used for the bio reactor) and the PVC used on the tank as hiding places for the fish. However, it has been several days now with the lights on during the day, sump light at night as well as the UV.

Sorry, i really don't know what the ongoing issue might be, but it doesn't seem like H2S now.