what killed this fish?

[Mattzilla]

found this angel dead as a door nail today for no obvious reason. as far as i was aware it was fine yesterday. all other tank inhabitants are fine

is this a worm sticking out of it's mout or part of it's insides????

http://farm3.static.flickr.com/2559/3972747547_10dae05dd1_b.jpg

thanks
matt

[ILLUSN]

doesn't liik lke a worm to me mate still it seems way too big to be his osephogus, is the belly concave at all, is the vent area clear?

[Mattzilla]

belly and vent as normal....

thanks for the phone call mate

as discussed i'm leaning towards it being it's osephogus