Cannot find fish please help

So I’ve been having a lot of fish die off and I don’t know why every time I get a fish I’ll make sure to take a cycled clean it regularly and make sure everything‘s OK a few months ago I had about almost all my fish die off I had one beta 2 guppies and one of my Harley Quinn but I had a one gup survive I put them in a nice tank and everything a few months later sadly passed away no one knows why one day he just couldn’t swim no more he was kind of old almost reaching a year old

but recently I got a new guppy something was off about him though every time I did a water change he would freak out lay at the bottom of the tank gasping for every single time when my other fish were fine so it’s been a few days he has gone missing he could’ve died in the tank or jumped out don’t see him on the floor and I don’t see him in the tank I have about 10 shrimps in the tank
What to do please help

 

If he died, shrimp could have ate him. Any snails you might have would have joined in thr buffet as well.

 

I agree all my dead fish are immediately eaten by amanos.

 

If he died, shrimp could have ate him. Any snails you might have would have joined in thr buffet as well.

ok to be honest I kind of hope that’s what happened because I don’t want my pneumonia to skyrocket the tank is only 3 gallons it’s a nano
And no there is no snails in the tank so if I leave it would that be ok

 

I might do a water change to be on the safe side, but yeah should be ok.