What could be taking my cory cats out?

[Ky'smommy]

first one had a large internal bleeding, second one went missing(still cant find him)The third was getting ready for babies i think. And i found him dead just now. and i noticed the one he was with. Was slashed down his side.
So that four out of four.
My tank has been very hectic since i moved them fighting among everyone.
i have 9 discus, some minnows. 2 loaches, 3 gouramis and a ram and 2 cory cats and bn pleco. Which is get close to over stocked so i am removing a few.
Now i know its not the discus.. They fight amongst each other and noone else. Which i think is because they are pairing up.
so my thoughts are loaches or gouramis..
when the corys were being wat i thought as maiting.. the loaches would chase them. Though nothing of it cause they were doing there own thing.
First of all My tank specs are fine. but i will check. but considering all discus and rams are fine im sure its not the water..
I have no unexplained deaths in months IN THIS TANK.. THey died durning the move or in other tanks.
I do every three day waterchanges so its not water quaility
i feed a varried diet..
Sooo im thinking its one of the other fish. so just looking for ideas..

 

[Jaybird]

I remember someone saying that clown loaches have small blade-like appendage near their eyes. Perhaps this could account for the slash?

 

[Ky'smommy]

they are yo yo's so maybe. i thought maybe so i was just wondering what else it could be.
and its just the cory cats.
No other fish is sick or hurt in the tank.

 

[Pleco]

Could they be fighting amongst themselves for territory or rank?

 

[Ky'smommy]

maybe. i thought they were starting to breed.
theres only four in a 80g.
so im not sure.
but i never seen them fight togther.

 

[Zagz]

Did you purchase all 4 from the same lfs? If so there is the possibility they had something right from the lfs, and the other fish are taking advantage of fish that aren't feeling well.

 

[coldmachineUK]

While botia loaches do have razor spines below their eyes, and while lochata (yoyo) are quite an aggressive species compared to others, I doubt they'd do that much damage. They might have chased your corys though, causing them to bump into tank decor such as sharp wood, or whatever else you might have. That might also explain the internal bleeding on one. Since loaches are usually more active late on you might want to check on them during the night and see if you can spot the culprit.