Strange depressions on male heads

[kadaborg]

Recently I have noticed that my male blue gouramis have developed a strange depresions near that heads. The rest of the fish have no similar symptoms. The quality of the water is good and all of my fish look healthy and are eating. Can anybody tell me if this is a disease or something else.
Please help.

[VoidParadigm]

It could be the beginning of hole in the head disease.

Got a picture?
What size tank are they in + what are the tankmates?
Was the tank cycled?
What brand of food are they fed?

[kadaborg]

The size of my tank is around 300 litres. I have other types of gouramis as well; dwarf, pearl, golden and snake skin. I also have 3 angels, beta fighter, bhali shark, 2 severiums and 2 ruby chiclids. I feed them mainly on TETRA products. I do water changes every forthnight and my aquarium has been matured; bacteria activity is ongoing.
Strangly enough this is happening to the males (blue gouramis) only. The other male gouramis; dwarf etc do not have this depression.
Checking on internet about hole in the head I found that this disease occurs mainly on oscars but not gouramis. I hope all other fish will not be affected. Enclosed find photos of this strange depression.
Thanks for your swift reply.

[VoidParadigm]

Just because a disease primarily affects one species does not nessicarily mean it can't affect others. Neon Tetra Disease for example can kill fish who have eaten Neon Tetras. Iridovirus is usually a killer of Gouramis (no, yours doesn't have it) yet many cichlids can die from it too.

I still say it's likely HITH, and it's likely due to overcrowding if all those fish are in the same tank.

Multiple species of Gourami in the tank means there is high competition for territory.
Gouramis should also not be kept with Cichlids except in large aquariums because they also share the same territory.
Bettas and Gouramis should not be in the same tank.

If all those fish are in the same tank, there's likely your problem and why your Blue Gouramis likely have HITH. They are overcrowded, which leads to stress.

Also; I'd suggest trying a different food, or at least supplementing the tank's diet with worms and veggies often. The only Tetra products I find to have any actual worth is their dechlorinator.

[gm72]

Really agreed with Void. Not much to add.