pregnant female violently attacked

[dirk_brijs]

I have 10 clown in a 160Gallon system who lived quit peacefully together.
2 couples formed with some smaller individuals roaming around.
Now after all this time finally one of the females got pregnant showing clearly a full belly.
Now one day to see that she got violently attacked by I dont know who having her dorsal fin a tail almost ripped off??
Is this normal behaviour??? Again before they never seem to have had any issues at least not that violent between each other?
I put her in a separate compartment now but I not too sure about this all? she doesnt look too good?
Can anyone explain?

 

[BonsaiNut]

Clownfish are some of the most aggressive and territorial fish in the ocean. Fish that live together peacefully for years will probably not do so if they become sexually mature. There are many, many threads like this one in the history of the forum. This is probably the singly most asked question here - "how many clowns can I keep together in a tank?". The simple answer: two safely. Any more than two and all bets are off.

 

[dirk_brijs]

I do understand but shouldnt be the behaviour be the other way around?
I thought with clowns the female became the larger dominant figure in the group especially when pregnant so how come someone out of the group of males would have attacked her?
Could it have been the other female but she is not sexually mature yet and for sure not even close to this pregnant female size?
This one has been the dominant figure in the group all the time but now when pregnant no more??
That was more the question I knew about their general behaviour but seems seem odd?

 

[SNAKEMANVET]

When clowns mature and start breeding they get very territorial,I have a mated pair of occs and a mated pair of true percs even my 240 8ft long tank was not enough room for 2 pair.I have anemones on both ends and they started fighting almost immediately.

 

[WDLV]

You said "2 couples formed." Everything you said after that was pretty much immaterial. That's a volitile scenario. You may get away with it for five years or five minutes but there are few "species" that will tolerate others in their nesting site for very long. Your tank is (I know this will sound weird) kinda small to have so many clowns. I would be thinking more on the lines of 500 gallons for that many.

I've had a large female latezonatus attacked by a much smaller female perideriaon and I had to remove the pinks to get it to stop. They had their own anemones feet apart and it still went South.