My Opaline Gourami has a big belly and is getting more black on him

[tellz]

my gourami's belly is looking really like big like he is prego and when i brought him he was a nice paleish blue wif harldy any black and now he is a nice blue and has heaps of black on him and looks pretty is he sick or is it normal he is only small compared to my 2 bigger ones,

my bigger male golden gourami is also turnig black and so is my female, thats why i thought it might b normal, and the male is really agressive and allways smashes in to my thermomitor and heater, and the female sometmes hides behind the filter or something,
but our other gourami is fine shes normal? is there anythign wrong with the others we have 2 tanks and in them we have


1 neon tetra, 4 rainbow sharks, 2 silver sharks, 4 sucking catfish, 6 feederfish, 2 of some type of sucking catfish that gets spikes on them, and black ghostknife 2 coolie loaches 2 oscars a golden black widow tetra 2 silverdollars and our 4 gouramis

 

[OrangeCones]

Could be internal bleeding and dead tissue. Gourami normally can't be housed together unless its a large tank with lots of hiding places to break up their line of sight.

What sized tank are the gouramis in?
Is it cycled?
What are the levels of ammonia, nitrite and nitrate?
What other fish are housed with the gouramis?

 

[tellz]

we just sold our 2 big ones but the littel ones r bye them selfs with the oscars in our medium tank not sure how bigthe tank is but the fish are still liteel so we have to move them in a few months to the other tank, n the levels r netural we just cheack it like once a week n adjust if need be,

 

[squidg]

What are you feeding them on??
I had a swordtail that went black due to worms i gave her as a treat, (well not much of a treat it turned out to be, she was ill.)

are you sure of the sex of them??
Some fish turn black during pregnancy...

The water tests dont show up any bacteria problems, so does your filter work correctly??

 

[OrangeCones]

n the levels r netural we just cheack it like once a week n adjust if need be,

What levels are 'netural'? And what are you doing to 'adjust'?