Again, i was shocked by the sight of my BGK fish who seems to nightly worsen in condition

. Yesterday all his tail and anal fin looked like that had gone through a paper shreder. In all my stupidity I let my older sister move him and the bichir to the 55
gal last night. Well, this morning when i went ot test the water perameters(still have yet to finish). I was happey to see all my fish out and about including the BGK. He looks really active, and happy. A second look and i notice the white tip of his tail is gone. It was bitten off or something u can see a speck of red where his flesh is 8O I havent noticed any aggression from any of the fish (well the gouramies are always duking it out between themselves but whatever) It seems unlikely that any fish would bite off a BGK fish's tale sense they can shock from it. I dont know whast to do

The only thing i can think of that might be a not fish attacker would be my artifical drftwood. It doubles as a cave(it has openings to its inside) and gets narrow in lots of places is it possible he could have scraped it really bad? Help!