Lost entire fish collection within 15 min. What cause it?

Hi,
Sad day for me.
Every single creature in my tank was dead in less than 20 min.
I just want to know some sort of answers (reasons/ causes) that may help me in future of fish keeping.
Here is the story:
-Woke up this morning and happy to see all of my healthy guys in the tank waiting to be feed.
-Shut off filtration system around 7 (sump and canister filter) prior to feeding
-Fed the tank with Ken’s premium flakes that including super brine shrimp, beef heart, plankton/ krill/ spirulina, vegetable, and spirulina with garlic/ paprika.
-Turn on filtration system at 8 then went to work.
-@ 8:30 received a call from my wife that stated all fish acting weird. All of them are flashing on their side, losing their control. Some already dead
-ask her to dose the tank with salt (1 teaspoon /10 gal)
-@ 8:48 received another call that stated all gone, everything is gone. Dead tank.
What cause it?
Water collected at 10:15 shows
-PH @ 6.6
-Ammonia @ 0.0
-Nitrite @ 0.0
-Nitrate @ 20
-Temp @ 84F
Tank is cycled, 50% WC 3 times/ week with aged water.
Gravel as substrate. Manzanita woods (in the tank for around 1 month), rocks, and fake plants as decoration
Disease? Is there any kinds of disease that can kill the entire tank within 20 min?
I started feeding the tank with Ken’s food since Wednesday. Prior to use Ken’s food, I fed the tank with tetra bits, FDBW, frozen BH/ bloodworm/ brine shrimp. Is food having anything to do with this?
Checked heater for possible crack that may cause electrocuted but found nothing unusual
Aftermath, I lost 13 discus (4 to 7 inches), 4 tetras and a cleanup crews with 4 fishes.

Ohh man so sorry to hear that. That is not a way to start out the day at all. Hope you get it figured out as I would have no idea what would wipe out an entire tank of different species other then maybe something that may have been on your hands and got into the tank????

Use any bug sprays, lotions, maybe took meds and had traces of it left on hands???? Try and think of anything like that since your water parameters all seem to be in check. Nitrates could be lower but will never wipe out a tank at only 20ppm.

Good luck and hope you get it stocked again in the future after a THOROUGH CLEANING.

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Originally Posted by xxbenjamminxx

Ohh man so sorry to hear that. That is not a way to start out the day at all. Hope you get it figured out as I would have no idea what would wipe out an entire tank of different species other then maybe something that may have been on your hands and got into the tank????

Use any bug sprays, lotions, maybe took meds and had traces of it left on hands???? Try and think of anything like that since your water parameters all seem to be in check. Nitrates could be lower but will never wipe out a tank at only 20ppm.

Good luck and hope you get it stocked again in the future after a THOROUGH CLEANING.

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Thanks for your reply
I washed my hand prior to feeding the tank. So I guess that I am clean.

So sorry. I just finished listening to Andrew Soh speak on all aspects of discus keeping. He says that when discus die all at once, quickly, it is always some sort of chemical poisoning in the water. Chlorine in your case maybe?
Barb

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Originally Posted by Disgirl

So sorry. I just finished listening to Andrew Soh speak on all aspects of discus keeping. He says that when discus die all at once, quickly, it is always some sort of chemical poisoning in the water. Chlorine in your case maybe?
Barb

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Can't be. the last time I do WC is Thursday. 50% with aged water and dosed the tank with prime prior to fill.

They probably died from poison or electricuted, fish dont die all at once in 20 mins. Im sorry for your loss, I know the feeling

I had that happen to me along time ago,turned out the wife sprayed frebreeze air freshener that morning and the mist apparently got into the water,everything gone within a hour.
Needless to say so air freshener allowed in fishroom .Not sure in your case but be careful with sprays colonge,perfume,hair spray etc we dont think about it some times but one slip is all it takes.
Sorry you are going through this believe me i know how you feel.

No harmful chemicals allowed inside the fish room and I always close the door because my wife loves to use air spray. I dont allow my kids to go inside the fish room unless if im present.

Really feel sorry for your loss. I know how hard it hits a fishkeeper's heart.
It must be poisoning or oxygen depletion. Do you usually turn off your filtration system for an hour everytime you feed them? Is that possible your oxygen totally depleted in your filtration system. When you restart it, the water inside filtration system dilute the oxygen level in the tank. Unlucky you just heavyly feed your fish, they need more oxygen than usuall. Combine these together, it could kill all the fish immediately.
Of course, it is highly possible some sort of chemicals enter the tank.

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Originally Posted by qiyanfeng

Really feel sorry for your loss. I know how hard it hits a fishkeeper's heart.
It must be poisoning or oxygen depletion. Do you usually turn off your filtration system for an hour everytime you feed them?

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Yes, I always turn off filtration system prior to feed the tank and it's last about an hour or less.
With oxygen depletion, fishes should stay on top of the tank gasping for air, am I correct? According to my wife who observed the disaster, no fish were gasping for air, they just flashing on their side and lost control until they die.
One time I forgot to turn back filtration system (probably 3 months ago) and it lasted for 8 hours. I realize my mistake when I woke up in the morning and found out all fishes stay on top of the tank and gasping for air but no one die.

Then, probably it's some sort of poison chemicals. Hope you can figure it out soon.

Sorry to hear about your losses. Is there any particular reason for turning filtration off? One hour should be fine, but why risk depleting the bacteria of oxygen if you don't need to do it? You mention that your kids are not allowed in the fishroom. I don't know their age or circumstances, but forbidden fruits are always the most attractive. I read a few reports by fishkeepers about kids "feeding" something to fishes and killing them. Something got into the tank and killed your fish. Another possibility is anaerobic bacteria. What is your substratate, how deep is it, and for how long have you had it? Especially in the case of sand substrates, a pocket of anaerobic bacteria can grow slowly and be suddenly released in the tank, killing all fishes.

I think that there is something more than you don't know about, something got in the water

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Originally Posted by DiscusBR

Sorry to hear about your losses. Is there any particular reason for turning filtration off? One hour should be fine, but why risk depleting the bacteria of oxygen if you don't need to do it? You mention that your kids are not allowed in the fishroom. I don't know their age or circumstances, but forbidden fruits are always the most attractive. I read a few reports by fishkeepers about kids "feeding" something to fishes and killing them. Something got into the tank and killed your fish. Another possibility is anaerobic bacteria. What is your substratate, how deep is it, and for how long have you had it? Especially in the case of sand substrates, a pocket of anaerobic bacteria can grow slowly and be suddenly released in the tank, killing all fishes.

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Just want to avoid food get suck in to filtration system so that was the reason I always turn off filtration system prior to feed.
My daughter is 13, she was sleeping during the disaster. but she never feed the tank without my permission. Anyway, I did not mention about not allow kid into fish room.
Gravel as my tank substrate, it about 3 in and I have it when I start the tank.

Sorry to hear that...... it's really weird, I'll think has to be related to poison, how? don't know but somethig got release suddenly in the tank, may be something inside canister filter, have you check that?