Gourami attacking other fish

I have one male opaline gourami. Suddenly it became aggressive and started attacking my molly. Please help.

If we have a single fish without any other fish of same species, do they show their frustration on tank mates?

 

Tank size?

 

Oplaline gourami are also known a the 3 spot gourami and are pretty well known for getting quite large (up to 6 inches) and territorially aggressive

 

Tank size is length - 18" width - 8.5" and height - 9.5". I have 1 gourami and 1 molly.

 

You should probably move the molly to another tank asap.

 

Yeah I moved it already, but why is it aggressive suddenly. Need to know the reason..

 

Tank size is length - 18" width - 8.5" and height - 9.5". I have 1 gourami and 1 molly.

Tank size is small. The dimensions looks like it's between 5-15 gallons. Aggression usually occurs when the aquarium is small, where there's little space for the fish to live peacefully. Just like people, fish need their own space.

 

I used an aquarium volume calculator and those dimensions came up as 6.29 us gallons. Opaline gourami requires at least 20 us gallons. As I said up there, they get as big as 6 inches and are quite an aggressive and territorial fish anyway, let alone in cramped conditions. It's probably reaching sexual maturity. I'd suggest getting a much larger tank or rehoming the lil guy

 

Is this a newly set up tank? Your profile says you don’t know what the nitrogen cycle is so I’d recommend reading up on that, also I agree with above, way too small of a tank for Opaline gourami.

 

I used an aquarium volume calculator and those dimensions came up as 6.29 us gallons. Opaline gourami requires at least 20 us gallons. As I said up there, they get as big as 6 inches and are quite an aggressive and territorial fish anyway, let alone in cramped conditions. It's probably reaching sexual maturity. I'd suggest getting a much larger tank or rehoming the lil guy

Tbh, even a 20 is too small for an opaline gourami.

 

Tbh, even a 20 is too small for an opaline gourami.

Yeah, I agree. I'm just going off fishlore's minimum requirements on their info page, for a single lone fish. I'd personally do no less than 55 if I wanted any other fish in the tank

 

Is this a newly set up tank? Your profile says you don’t know what the nitrogen cycle is so I’d recommend reading up on that, also I agree with above, way too small of a tank for Opaline gourami.

A month ago