What could be attacking my pangesius catsharks?

I'm assuming it's something nocturnal, but I thought everybody was pretty friendly.
I have two 12 inch pangesius catsharks, which have been appeared to be attacked the past few days when I would turn on the light in the morning. One died today from wounds. I'm not quite sure what is attacking them. I assume it's something nocturnal. Currently I have:
Two black KuhlI loaches (approx 2.5 in)
One opaline gourami (adult) - housed together for at least 2 or 3 years.
One angelfish (juvenile)
One violet goby (approx 12-14 in) - housed together for about a year.
A few zebra danios, a few mystery snails, a cory cat, and a nerite snail.

I'm assuming it's something nocturnal. My guess is it's the goby, but my goby has never been aggressive before. He's a big coward most of the time.

The wounds are very severe (the skin has been taken off in many areas), and they're mostly on the face and gill area.

Thanks for any tips!

 

Welcome to fishlore!
What size tank?
I'd guess either the goby or the gourami.

 

They're probably getting spooked and crashing into the ends of the tank or the decor. Must be a huge tank. They grow to 3-4'. They're shoaling when young and often are panicky when not in a group.

 

Thank you
Hampalong, I think you may be right. They have shown that kind of behavior since I got them, "spazzing" out constantly. My tank is a 55 but they constantly hit the walls, decor and the ceilings when the water level is up. They've never actually gotten hurt this badly from crashing into things before, though. My guess is that they're getting attacked, then spazzing out and giving themselves additional injuries... But my goby has never been aggressive before. The gourami also keeps his distance.
I'm going to leave the light on tonight and see if that helps, I suppose. Still very confused!

 

Are you planning on getting a multiple thousand gallon tank for them? If not, I'd rehome.

 

They don't need anything to be attacking them to do this. They're doing it because they're in a tiny tank. These fish (they're Catfish btw, not 'catsharks') swim constantly covering huge distances. They just can't function in a tank this small. They grow 3-4' or more and need to be in a shoal.

Silver/Bala Sharks are the same, and dollars.

 

Also your Cory cat should be in a school and not on his own.

 

Not to dogpile you, but the violet goby needs to be in a brackish tank that's about twice the size of your 55 gallon.

 

Could be the angelfish even though its juvenile they are quite aggressive . I had them before n dey seem to kill any tank mates regardless of size