Parasite? WHAT IS IT

[Jhklyy]

My large adult angel passed away sometime today, I saw when I got home..
My water parameters were 0 ammonia. 10 nitrates, 0 nitrites. I did a water change yesterday but again my levels were fine.
My angel acted normal and there was no bloating.
I checked for a wound and found a little puncture wound and thought he poked himself on something. After looking at the pictures I took it looks like a parasite sticking out of the puncture hole right by his fin. I went back and looked at the fish and did not see what I saw in the picture.. only the little flap of skin that was injured.
I have raised mystery snails in this tank and I have recently purchased 3 other angels

Whatever it is, I'm not the only one seeing it right? It looks EVIL or it could very well be its guts but I know them snails didn't poke a hole in the fish, and they did not eat into him at all ��

 

[Jhklyy]

Also to add: 55 gallon, 1 70 gallon hob, 2 big sponge filters.
Used to be my adult angel, and 3 babies (2 are a little bit bigger than the tiny one) and a handful of myself snails I raised, 1 baby brislenose pleco.
I do water changed every 2 weeks
I've had my adult angel for more than a year , the young ones for 3 ish months
They eat a variety of frozen foods and hikari vibrant bites

 

[Andy Sager]

Sadly, many of the larger cichlids can carry internal parasites that make their way out of the fish anywhere they can. The soft tissue behind the fins is an easy exit. Snails can be intermediate hosts for a number of parasites and all it takes is for an infected snail to get eaten to start a whole cavalcade of problems.
Since you have snails in with your angelfish, you might want to treat them all with products like Expel-P or Paracleanse by Fritz Aquatics or similar medications. When the parasite leaves the fish, it's usually to multiply so you would need to do regular gravel cleaning and watch for more wounds in the fish.
The good news is that more often then not, worms/ parasites leaving the fish's body do not usually kill them but does leave an open wound that can get infected. You have to watch out for secondary infections.
Hope this helps.