Im loosing fish, pic. attached

My big question is who would be fighting? I thought that one Butterfly went after the other, but then one died so there was no one to attack him???????Hmmmmmmmmmm
 
How big is the tank? Damsels are very aggressive fish bulling fish that are bigger than them, Crabs would not of done this, they where just getting food (everyone has to eat) Parisite is the likely what killed the other, what are your water specs? QT, treat and hope for a good outcome would be my suggestion. Remember also that fish need a good daily diet that will help strenghten their ammune system, prevention is alot better than treatment....trust me on that one.
 
The tank is 90 gal. The crab is actually trying to catch fish, he runs up and down the LR with his one arm out.
Where would a crab (fiddler crab) come from, I've never seen them is stores.
That's getting away from my problem......what do I do about fish, the others in the tank are fine, but I want to add more the tank looks empty!
 
The area around the mouth looks like it was caused by a bit of how's your father.
 
I am sorry about your fish.

Great pic and comparison drobes- good info to have.

The only reason I suggested fighting is because I had a fish a long time ago with signs of disease- heavy breathing, faded colors, stopped eating, red markings, etc. Decided to treat and didn't realize until it was too late...another fish (yellow Tang) was bullying it. I had no idea. I just like to consider all the options before people start dosing meds and doing hypo or freshwater dips.

My big question is who would be fighting? I thought that one Butterfly went after the other, but then one died so there was no one to attack him???????Hmmmmmmmmmm

I wrote I thought it could've been the damsels. Again, really sorry about your fish. It sucks having fish die.
 
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