Possible Culprit, chunk missing from Zebra Danio

[Lt.]

My stock:
7 tummy nose tetra
3, 3 1/2 inch angelfish
2 1/2 zebra danio
2 Ssilver hatchets
1 CAE
3 neon terra
6 cories
Assorted shrimp and snails, all micro

Tank:
Medium to lightly planted, 45 gallon. Orange gravel substrate

Problem:
Came home, looked in tank, saw the poor little zebra danio and upward struggling to swim. Has large chunk missing in front of dorsal fin. On left (his left) side of fish, by pectoral fin, bite marks/wounds, not too severe looking. Do I try to save him or euthanize him? How do I go about it either way? No hospital tank available, have aquarium salt, stress coat, can get anti bacterials if necessary.

Question:

Who done it? I've never had any aggression issues before. Pics will come later.

 

[Wiggles24]

You have two types of potentially aggressive fish your cae and the angels. Highly doubt this was the work of your algae eater it was I'm sure one of your angels

 

[Fishfur]

I'd think euthanasia, if you can't separate him to another tank. Chances are, now he is damaged, the fish who first attacked will do so again and either bite him badly enough to kill or continue to maim him 'til he dies of stress or infection. Not a kind way to go. Damaged fish swim erratically, which tends to excite predatory tendencies in other fish.

I think the Angels are the culprits as well. They can be quite nasty sometimes, and if they are preparing to spawn, will drive off any fish coming near the chosen site. Don't know if your Angels are spawning but it might be the reason for aggression suddenly beginning when there hasn't been any before.