Killer Attack Fish

Whoa. I got two blue gouramis (male and female) a week ago and at first they were extremely sweet and always close together. But now the female just picks at the male, always chasing him or biting him.
They're really freaking out me and the other fish (panda cories and cherry barbs). I am wondering how they changed so quickly and why this is happening. the tank is 55 gallons and heavily planted (they could easily avoid each other) so why????

 

Gourami's mixing together always ends up as a death wish. Gourami's are closely related to Betta fish and often times even with a large tank they go at each other. They should be alone or in harem's, males with 4-5+ females. A harem should have a large tank.

Dwarf Gourami's usually never need buddies. Honey Gourami and Pearl Gourami are examples of some that appreciate groups of their own species.

When they are juveniles they sure do tend to hang out together after adulthood hits and the male want's to breed the female grows stress with the male constantly wanting to breed it's harassing.

I would move one of them to another tank. They won't get alone unfortunately.

 

The nature of their personality?
They are getting comfortable enough with their surroundings to develop territories?

I really don't know about Blue Gouramis but personally I don't ever start to relax until the about 3 month mark.
Even then, things can always change.

 

Sure you don't have two males??? Agression of a female to a male is not normal to me.

 

I definetly don't have two males. i've checked and double checked. The female is older so I think she'd be showing signs of malieness by now. Thank you for your help I am going to return her.

 

Please realise two just bought fish won't immidiately be a couple. They have to learn to know each other better. If they don't wound each other you could give them some more time????