Another Fry Disappeared Over Night,

[FishBlast]

This morning I've fed my fish at 8 AM, all fry were there, only that Hoppy, the pink fry, was still sleeping next to the filter, with his dorsal fin lowered.
All other fry just went for the powdered daphnia, along with the adult fish. He just sat there next to the filter, no interest in food.

I went back to sleep and woke up at 12 PM. Hoppy was missing. I've searched all over, no sign of him.

Did a water test, both ammonia and nitrite came as 0. Yesterday, I had done a 50% water change (4 buckets of 11L).

A short while after declaring Hoppy missing, I fed the fry again with powdered daphnia, and noticed that Sushi (my biggest fry alive) preferred to peck the sand instead of joining his siblings to eat. A bit later, my adult male swordtail and Sushi both pooped what seemed to look exactly like white, somewhat metallic thread, but it wasn't long.
It looked exactly like this kind of thread:

Then the adult male continued to poop normally, black.

It could be either hexamita or a nematode, but no idea what to use or what we have available here. Is there something that's a 2 in one that would treat both? I'll observe these two for today, I'm not entirely sure what I'm dealing with here.

 

[FishBlast]

Now another fry is spazzing around, breathing fast and swimming backwards, sitting on the sand. Not even other fish scare him away. Re-testing nitrite.

 

[FishBlast]

Result for nitrite = 0 again. Chrome started pecking the sand for food, but his breathing's still too fast.

 

[FishBlast]

Well, Chrome disappeared too. Though his symptoms had stopped and he was eating, I don't know what happened to him, but he's nowhere to be found. I moved my remaining 2 fry in the box to see if they're ok.

 

[zain611]

How big was that fry when it went missing because fry can eat smaller fry of its kind. when my guppy was giving birth for the second time i put the female in the hatchery with my other fry in it which it gave bith to before and put the grill in on top of the fry and when fry came out and went into safety my bigger fry chased it and devowered it

 

[FishBlast]

How big was that fry when it went missing because fry can eat smaller fry of its kind. when my guppy was giving birth for the second time i put the female in the hatchery with my other fry in it which it gave bith to before and put the grill in on top of the fry and when fry came out and went into safety my bigger fry chased it and devowered it

They were in with adult fish: 4 swordtails and a 5 inch hoplo.
First fry that disappeared was like 2 cm, second was 1 cm.
The first one refused to eat that morning. It was gone by noon. But too big to fit in any fish's mouth.

The second one was breathing fast for most of the day, and resting on the sand. The adults did not bother him while he was there. Last time I saw the little guy, he was at the surface of the water, he was no longer breathing heavily, but his tail was hanging a bit limp. 30 minutes later, he was gone. The hoplo could have eaten him and the other one, but he could have eaten the last one while it was lying on the sand, and yet he didn't, he just passed it by, several times.

The odd thing: The first ever fry I had lost like a month ago, was 3 cm, way bigger than any of these. Certainly didn't fit in any fish's mouth, even if they forced it. But it disappeared over night. The day before that, she ate 3 bloodworms, one after the other, then sulked in a corner of the tank, on the sand.

They could not have jumped out either, the lid is quite tight sealing the tank, no holes through which the fry could have jumped.

 

[N0body Of The Goat]

Maybe your Hoplo has suddenly remembered that he/she is supposed to eat young fish?

 

[FishBlast]

Maybe your Hoplo has suddenly remembered that he/she is supposed to eat young fish?

How does he fit a 2 cm fish in there though?
But both had something I don't understand: why 1 wasn't eating and the other was breathing fast and had his tail lowered?
Could that large water change affect them? They started acting weird the next day after that.
I have separated the last 2 fry into the fry net, but 1 of them is almost always hiding.

Also, I'm watching out for a possible Hexamita infection. So far only one incident of white feces of an adult and a fry same time, but haven't seen it since the day those 2 fry disappeared.

EDIT: In that pic in my signature, you can see the first fry to disappear that day. The pink fry that's on the sand, near the hoplo. It was a bit bigger than in the pic last time I saw him.

 

[zain611]

Its like my bigger fry, they cant fit a new born fry into their mouth but they tear it apart

 

[FishBlast]

Its like my bigger fry, they cant fit a new born fry into their mouth but they tear it apart

If that would be the case, then my adult swordies might have shredded them as soon as the fry went weak enough. The hoplo can't even shred his flakes properly, it takes him so many gulps to just grab a flake, and that's soft food already.
But I never get to see how they disappear, all I see is them sulking somewhere for a while, with tails lowered, like this:

but the swordtail fry version. And not with the rotten part, just tail hanging like that.
Every time a fish of mine did that, it meant they were close to death.