My guppy disappeared in less than 2 hours

Tank
What is the water volume of the tank? 20 gallon
How long has the tank been running? Smaller tank was running for years. Moved everything inside to new tank (plant, decor, heater, sand). New tank running for about a month, plant flourishing and water parameters good.
Does it have a filter? Yes
Does it have a heater? Yes
What is the water temperature?
What is the entire stocking of this tank? (Please list all fish and inverts.) 4 corydora, HAD 3 guppies, now have just 2 guppies, and 1 endler

Maintenance
How often do you change the water? Once per week
How much of the water do you change? 50%
What do you use to treat your water? Imagitarium water conditioner
Do you vacuum the substrate or just the water? I swirl up the debris off the sand using my siphon and get it that way. Did vacuum when I had gravel.

*Parameters - Very Important
Did you cycle your tank before adding fish? Yes
What do you use to test the water? API master test kit (liquid)
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Ammonia: .25ppm
Nitrite: .25ppm
Nitrate: 10ppm
pH: 7.6
I recently found out that parasites have been rampant in Corys from the pet store I buy from, so I've been treating them. 2 showed symptoms of parasites. One of those 2 died sometime last night (body intact) so the body probably caused the ammonia/nitrite spike. They're usually 0.
Guppies did not have parasites at this time, I already treated them.

Feeding
How often do you feed your fish? 2x per day
How much do you feed your fish? Small pinch 2x per day, and 2 sinking carnivore pellets only at night (for corydoras)
What brand of food do you feed your fish? Tetra color flakes and hikari sinking carnivore pellets
Do you feed frozen? No
Do you feed freeze-dried foods? Not sure, see above

Illness & Symptoms
How long have you had this fish? A month or 2
How long ago did you first notice these symptoms? Disappeared last night ~6:30 PM
In a few words, can you explain the symptoms? He was perfectly healthy and loved playing in the bubbles. No parasites or illness
Have you started any treatment for the illness? Was using General Cure for corydora I added
Was your fish physically ill or injured upon purchase? No
How has its behavior and appearance changed, if at all? No, bubbly and happy

Explain your emergency situation in detail.
(Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)

I've been adding fish to my (yes, cycled) tank. I stopped buying fish for temporary reasons. So, I've been adding fish little by little, and its common for some to die. I only have guppies and corydoras. Every time a fish has died I find the body untouched, usually died overnight. I scoop the body out as soon as I find it. My guppies have been super healthy and playful. I was admiring them all day while working (I work from home), and right at 5 I saw they were all well. I left and came back less than 2 hours later and one guppy was gone! I checked all around the outside of the tank, although I have a lid. I checked inside the filter because they like to jump in the stream. I only have 1 small decoration, nothing in there. I have sand so he's not in the sand. I checked all in the plant. Between the filter and the glass... Nothing. I'm so confused. Has anyone had this happen? Its unlikely he was eaten because they haven't eaten each other with any other deaths and last I saw him he was super healthy, and I was only gone for about an hour and a half.

 

Hmm, this is strange. You’ve checked everywhere the fish could go, so suggesting looking anywhere else is out of question. However, I will enquire: do you have any pets that could potentially open the lid and snag fish from the tank?

Please use the emergency template. I think it’s important to know whatever is going on, and hey, we might gather more clues from using it.

A picture of the tank might also be of aid.

 

I've had that happen a couple times, and always with guppies. I'm about half convinced they can teleport.

 

some fish eat other dead fish, do you think that happened?

 

Hmm, this is strange. You’ve checked everywhere the fish could go, so suggesting looking anywhere else is out of question. However, I will enquire: do you have any pets that could potentially open the lid and snag fish from the tank?

Please use the emergency template. I think it’s important to know whatever is going on, and hey, we might gather more clues from using it.

A picture of the tank might also be of aid.

Thank you! I updated now and attached a picture. So weird.

I've had that happen a couple times, and always with guppies. I'm about half convinced they can teleport.

Haha! That's might be right

some fish eat other dead fish, do you think that happened?

I don't know, I thought that at first, but every other fish death there was a completely intact body, even from overnight. They never ate the bodies. Plus I'm not sure 2 guppies and an endler could eat a whole guppy in less than 2 hours. And he was perfectly healthy when I left.

 

Reduce the amount of food being fed....and try to get ammonia and nitrite to 0. Any traces of them in the water is not good, I wouldn't add fish to the water until that is resolved....

 

Reduce the amount of food being fed....and try to get ammonia and nitrite to 0. Any traces of them in the water is not good, I wouldn't add fish to the water until that is resolved....

Thanks, its usually 0 but its a little high because I just took a dead cory (parasites from the pet store) out of the tank just before taking the reading. It was dead overnight. I added bacteria to the tank just now. I'll try reducing the food!

 

Thanks, its usually 0 but its a little high because I just took a dead cory (parasites from the pet store) out of the tank just before taking the reading. It was dead overnight. I added bacteria to the tank just now. I'll try reducing the food!

Good luck! Just fyi, for a tank with about 16 guppies + 1 pleco + 1 catfish I feed it about once/twice a week.

 

I had a parasite come in with plants and kill 3 adult guppies before I realized what happened. I used a canine dewormer and now no dead guppies for last 6 weeks.

if your cories were sick, then treat the tank. I've used dewormer with my 7 false julii cory cats, no deaths in my 20 tall tank a few months ago for planara that was killing my shrimp.

 

I had a parasite come in with plants and kill 3 adult guppies before I realized what happened. I used a canine dewormer and now no dead guppies for last 6 weeks.

if your cories were sick, then treat the tank. I've used dewormer with my 7 false julii cory cats, no deaths in my 20 tall tank a few months ago for planara that was killing my shrimp.

What kind of canine dewormer? Very curious since fish meds are pretty much banned in Canada now.

I've been there with the disappearing guppy - it drives you nuts - I find the body always turns up eventually if you keep checking