Angelfish keepers advice

Hi, I've had my angelfish for 9mth and I noticed the end of her anal fin has broken off, first I thought it was my fish nipping her but I've observed the tank even at nightime and no one is bothering her? I'm wondering if she's getting bumped when sleeping she's either on the bottom or at my filter.
I'm keeping the tank clean Dailly changes but it gets better then splits again. Will this cause her stress and infection? I do have someone who will take her but if I can help I'd rather do that.
Sorry for the long post.

From your information I would tend to suspect fin nipping. What other fish species are in the tank, and how many of each species?

Thanks for the reply
4 elephant noses and 8 congo tetras, haven't seen anything myself even at night.

Elephant nose 4 said:

Thanks for the reply
4 elephant noses and 8 congo tetras, haven't seen anything myself even at night.

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The elephant nose is a nocturnal species, so this is one issue. Angelfish and Congo Tetras are not, and nocturnal fish can really stress out angelfish. Even without actual physical interaction. And stress is the root cause of more than 90% of all disease and problem issues with aquarium fish. The Congos should be OK, but if this were me I would remove the poor angelfish.

I only have my 30 gallon shrimp tank sadly, but someone has said they'll take her. Thank you for your advice. I'll rehome her I don't want her stressed