Serial killer in my tank!

I have a 45 gallon community tank which has been running now for 3 months. The fish in the tank have been around for over a year. I’ve transferred them from tank to tank as I upgraded. Never had any problems. I had originally 1 pleco, 1 angelfish, 5 black skirt tetras, 5 danios, 1 platy, 3 corys & 4 other tetras that I cannot remember the name. Over this past weekend I purchased 2 mystery snails, 2 nerite snails, 4 neon tetras, 3 platys & 2 otos. Fish were purchased on Friday, Saturday morning I wake up to find 2 of the new neon tetras missing. 2 days later the other 2 are missing. Mind you they were kinda small so I figured someone kept having midnight snacks. The next day I can no longer find 1 of the 2 otos. The day after that I find an oto on my tile floor. The little guy climbed up the air line & got out through the 2x4 inch cutout for the filter intake. Mind you now I have 2 otos gone. Never found the first missing one. The next freaking day I find 2 of my unnamed tetras missing. I’ve had them for almost 2 years. No floaters, just gone! Yesterday I found my original platy about half eaten floating around the filter intake & bones from one of my original tetras in my gravel. At first I thought it was the remains of the squash I had feed the night before. Today I find one of my danios with a wound to his side almost like something bit or sucked on him. He was still swimming like normal. 1 hour ago I find him dead floating around by the filter. What is going on?? Now I am noticing that one of my original black skirt tetras looks wounded. He seems very flat near his belly unlike the other 4 that look fat. Like something squeezed him. I can’t figure this out. Can the mystery snails be hunting my fish? There is no way they ate the neon tetras, that was probably the angelfish or the danios since the neon tetras were very very small but the other fish that have perished were at least an inch or more. My pleco is about 3 inches, could he be the one? I make sure he gets his or her algae wafers & squash every other day.

Basically I have fish that either keep disappearing or are getting eaten every night. I have no cats, there is a glass lid on top. Started after I bought new 4 snails & 9 new fish, 4 neons, 2 oto & 3 platys.

 

How big is your angelfish?

 

I have a 45 gallon community tank which has been running now for 3 months. The fish in the tank have been around for over a year. I’ve transferred them from tank to tank as I upgraded. Never had any problems. I had originally 1 pleco, 1 angelfish, 5 black skirt tetras, 5 danios, 1 platy, 3 corys & 4 other tetras that I cannot remember the name. Over this past weekend I purchased 2 mystery snails, 2 nerite snails, 4 neon tetras, 3 platys & 2 otos. Fish were purchased on Friday, Saturday morning I wake up to find 2 of the new neon tetras missing. 2 days later the other 2 are missing. Mind you they were kinda small so I figured someone kept having midnight snacks. The next day I can no longer find 1 of the 2 otos. The day after that I find an oto on my tile floor. The little guy climbed up the air line & got out through the 2x4 inch cutout for the filter intake. Mind you now I have 2 otos gone. Never found the first missing one. The next freaking day I find 2 of my unnamed tetras missing. I’ve had them for almost 2 years. No floaters, just gone! Yesterday I found my original platy about half eaten floating around the filter intake & bones from one of my original tetras in my gravel. At first I thought it was the remains of the squash I had feed the night before. Today I find one of my danios with a wound to his side almost like something bit or sucked on him. He was still swimming like normal. 1 hour ago I find him dead floating around by the filter.what is going on?? Now I am noticing that one of my original black skirt tetras looks wounded. He seems very flat near his belly unlike the other 4 that look fat. Like something squeezed him. I can’t figure this out. Can the mystery snails be hunting my fish? There is no way they ate the neon tetras, that was probably the angelfish or the danios since the neon tetras were very very small but the other fish that have perished were at least an inch or more. My pleco is about 3 inches, could he be the one? I make sure he gets his or her algae wafers & squash every other day.

Basically I have fish that either keep disappearing or are getting eaten every night. I have no cats, there is a glass lid on top. Started after I bought new 4 snails & 9 new fish, 4 neons, 2 oto & 3 platys.

Check the filter?
Just a thought.

 

New fish might gotten eaten by angel or just died to stress or illness due new environment and got nommed on by other fish that will eat dead fish bodies for sure (also plecos, they dont solely live on plant matter and do scavenge) . Uneaten fish remains very likely cause spikes in ammonia in your tank and might kill other fish until the problem is fixed.
First I would try to find any remains (also in filter) and do water changes 50% now and smaller daily until ammonia is down, treat with water conditioner (like Prime) that detoxify ammonia.
Otos are very sensitive also so any ammonia or high nitrites/nitrates might make them perish very fast.

For the future I would suggest having actual schools of fish like tetras, cories, danios and otos ( atleast 6, preferably 10 + of one species to reduce general stress of fish). Angel fish get big enough to snack on smaller tetras if they just fit in their mouth.

 

I will go with the angelfish. It's a cichlid and won't be nice to any new additions. Once dead the snails make a quick meal with the fish. And like stated above the pleco probably helped.
Also what kind of pleco? Some are carnivores and might try to make a meal of small fish.

 

Ive also heard bristlenose plecos getting aggressive and overly territorial sometimes.

 

How big is your angelfish?

About 4-5 inches, fist size.

How big is your angelfish?

About 4-5 inches, fist size

I will go with the angelfish. It's a cichlid and won't be nice to any new additions. Once dead the snails make a quick meal with the fish. And like stated above the pleco probably helped.
Also what kind of pleco? Some are carnivores and might try to make a meal of small fish.

I will go with the angelfish. It's a cichlid and won't be nice to any new additions. Once dead the snails make a quick meal with the fish. And like stated above the pleco probably helped.
Also what kind of pleco? Some are carnivores and might try to make a meal of small fish.

I think it’s a common pleco.
I have a prefilter sponge on the intake of the canister filter so I don’t think they are in there.

 

About 4-5 inches, fist size.

About 4-5 inches, fist size


I think it’s a common pleco.
I have a prefilter sponge on the intake of the canister filter so I don’t think they are in there.

My bet is on the angel fish having a late night snack. Check your water parameters though to make sure that isnt causing the problem.

 

The water seems fine. Water change was done on Monday, 80%.