Ctenopoma acutirostre help.

[archers]

I have had my Ctenopoma acutirostre for about 3 months, he is in a 55 gallon with
1 4" archer fish
2 2.5" angels
1 2" pictus catfish
1 6" ropefish
The Ctenopoma in question is about 5",
Recently i have noticed a "spot" on him that wasn't there before. At the beginning looked like a scale had fallen off or had been damaged in some way so i left it seeing as he looked healthy and was still eating thinking it would heal by its self. This morning however the "spot" seemed to look infected and there was a whispy tendril-ish thing hanging off of it there was also upon further inspection some brown material in it that was never there before. all of my water parameters are good the ph is around 7. my question is...
1. what is this
2.how to get rid of it
3 what can i do to prevent it ever happening again

 

[COG Commando]

Pictures will help with an I.D. of the affliction, as it's hard to tell what it could be simply from a description.
It could be an anchor worm, though, I suppose.

 

[archers]

i will post pictures, i had anchor worm a while back in a 10 gallon this looks nothing like it at all.

 

[archers]

https://www.youtube.com/watch?v=SOkjTasTlUE&feature=youtube_gdata_player this is a video of the fish I gave up on trying to get a picture but you can see near the end the spot its just behind the fin I dont know the ailment could you help me maybe diagnose it?

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