I killed all my lovely fish :(

[MichelleN]

Came home late last from an overnight anniversary trip. Noticed on the way to bed my 29 had cloudy water - bit it was so much worse!  Little bodies everywhere! Temperature read 76 and heater was plugged in but not running (its set to 74) and does not look cracked or wet inside. No one got shocked pulling out bodies.  Surprisingly we realized as we cleaned up the casualties and changed out water that 3 cherry shrimp and 2 Octo cats are still alive.  But the other Octocat, "blue" our drawf gourami, 6 red Glow tetras, my darling little pygmy corydoras and the 6 still juvenile honeys my husband placed in here to grow out a bit - all lost.  This is an 8.5 month running low tech planted tank.  I had given all the tanks repashy in addition to usual morning flakes and nano pellets.  I must have messed up and fed this tank twice, and it didn't look like they had chance to eat much, as I could spot the excess food as we cleaned the tank.  The ph and ammonia indicator cards we keep in there looked the same, but we don't trust them that much, so I pulled out water to test before we added any new water, just to know, and to punish myself a bit more I guess. I was expecting very high ammonia and drastically changed ph.  But the water parameters tested as they normally do for this tank.  That surprised me so I tested again, breaking out new unused ammonia test bottles just to be sure.  The ammonia read light yellow, maybe a very faint hint of green in the API test but not near the .25 yellow. Nitrites zero blue, not at all purple, nitrates about 20 (harder to read at night).  The tank is planted and nitrates used to run between 5-10 in this tank between water changes, but as the honeys have grown it has been between 10 and 20 just in the last month. 

My ph has always been difficult to call because it reads right at darkest blue (7.6) on low test, but a light orange (7.4) on the high test, so we call it 7.5 to 7.6 and just watch to make sure it's not swinging around. The colors were still in that usual for us in between range. 

 It's just so odd to have the tests look in the ranges normal for this tank while all my lovelies are dead! If I killed my fish because I overfed, which I am sure I've done, I'm not trying to escape that, but shouldn't my ammonia be sky high?  Could the ammonia spike, killing so many fish and then bacteria catch up and convert to nitrates before we returned and before the bodies started to depose? Was the cloudiness the bacteria bloom pulling that off? We left Tuesday at 8am, got back Wed night about  9:30 pm. 

The other suspect is Sunscreen.  It's a bit hard to be positive as we were in a hurry and I'm questioning everything now,  but I think it was after I applied Sunscreen to my face and legs, then on a subsequent pass by the 29 I decided to remove the shrimp cave because  earlier in the week one of the juvenile gourami had managed to trap itself inside. It was an impulse and I didn't think to wash my hands first. I'm not certain of the timing. So I blame myself more for the food, but my husband leans more to the sunscreen. Probably the combination, two stressors, then once anyone fish died, a chain...

After some debate we decided it was probably best not to move the poor survivors to one of other tanks, since we don't know exactly what happened.  So we stopped short of 50% change last night, then did another change this morning and plan to do additional smaller water changes over the next week and see if they continue to pull through. So far the few survivors seem to be doing fine.  But all my other poor fish 😢 im heartbroken and feel so bad.  

Edited May 21, 2021 by MichelleN

[xXInkedPhoenixX]

I'm super bummed for you, what a terrible thing to come back to after what was supposed to be a nice get-away. I'm sure you want to know exacty what happened. You don't happen to have any Poly-filter do you? The reason I ask is I usually put a small square in my tanks and whatever toxins it absorbs it changes an appropriate color. This would help you trouble shoot what it could have been. There apparently have been some instances where it turns a color that's not usual and the company may be able to help ID what it could have been. My pieces usually turn dark brown, which is the indicator for harmful organics (cause ya know, everybody peed in the pool). I know you've already probably changed a lot of water, but it's a handy tool as far as I'm concerned, I always have some. 

Edited May 21, 2021 by xXInkedPhoenixX

[MichelleN]

No, and thank you I looked that up and we don't.  But we do keep both a bit of Puragen and since our tap contains more phosphates that we'd like, some Phosguard in the HOB.  They both also typically turn yellow- brown when ready to be recharged or replaced. Which was fairly recently so we can pull those bags and see if they look different. 

Edited May 21, 2021 by MichelleN

[TheAdmiral]

Sorry for your loss, We've all been there. Absolutely was the sunscreen. It's hard to overfeed in a heavily planted (I'm assuming low-tech means heavy plants) tank and you are right, overfeeding is not what kills, it's the resulting NH3 spike from decaying/uneaten food, and even that takes longer than a day. 

Chemical sunscreen on the other hand, (which even humans should not use), is shockingly toxic to aquatic life. Not saying that a mineral sunscreen would have been safe, as they are shown to be harmful in larger quantities as well (but you and your family should only use mineral sunscreens!)

I always wash and dry my hands before going into the tanks (again, after learning the hard way)

Edited May 21, 2021 by TheAdmiral

[MichelleN]

@ xXInkedPhoenixX

No unusual colors, but the puragen seems much darker than I'd expect at this time since it was recently changed out. Maybe that's another part of the mysteriously normal appearing water test tubes. No recharging this time. 

Edited May 21, 2021 by MichelleN

[MichelleN]

@TheAdmiral

Yes, I'm thinking more so now also. It's hard to reconstruct the timeline afterwards and trust hindsight, but it fits. I didn't reach into any of the other tanks. Just this one.