Urgent - Bloated Dwarf Gourami, Fast "breathing"

Yesterday thought Mr Gourami looked a little fat but decided it was the lighting. Today, my husband said he didn't dash up at snack time and has been hanging around at the bottom back corner. He too noticed he looks bloated.

He has swum around and come to the top, tummy definitely bloated.

Please advice! I will google the symptoms and search but quick advice from those that know is required!!
Thanks

No doubt ppl would appreciate more details to be able to help.

6month old tank, due a water change Saturday. Just checked:
ammonia: 0
Nitrite: 0
Nitrate: ~10 to 20ppm

Tank mates are:
 3 guppies, 7 neons and 5 panda corys... all alive, and actively swimming about.
Didn't notice an appetite drop in Mr Gourami yesterday and day before he was fighting the corys for a half tablet!!

I am happy to do a wtr change to improve the quality in a bit but I am sad somebody has become ill.
I klnow we keep them in a confined water source - explained to the children that we have "fresh" air blowing all the time but fish in a tank do not so are susceptible but still feel disappointed in myself 

Will try and get a pic... difficult to get good ones even when they are having a slow day!

No visible injury, gills look good colour but distended abdomen begins behind gills so not great view.
Scales spread due to distension of tummy.

im going to do a water change and then feed dinner... just asked next door if she had any frozen peas - in case he's constipated, meant to help aren't they?? (err.. the cooked ones not the frozen!)

While I don't have experience with dwarf gourami, I do have plentiful experience of bloated goldfish and goldfish with buoyancy problems. On the basis of that experience, I'd advise:
* feeding frozen, chopped peas ie blanch a pea so that the shell slips off easily; then keep chopping each of the halves into as many small morsels as you possibly can - put that in near the filter outlet, so that it disperses around the tank and the affected fish can get at least some to eat
* feeding frozen/live food (eg bloodworm, brineshrimp, daphnia) - like peas, this should also induce a clearout if there's any intestinal blockages causing the problem (such as having consumed the majority of that tablet a few days ago)
* frequent water changes - even 10% daily should help
My next stages of treatment, if the above didn't work, were aquarium salt which often had an overnight turnaround effect (but this isn't advised with many species of tropical fish so I'd avoid that if in any doubt) and finally medication (for bacterial infection).

If the scales look pineconed all over (as opposed to just slightly spread where the tummy is distended), then this indicates dropsy. There's no mistaking the pineconing look - it's the first thing you'd notice if it's happened.

If he looks as though it's struggling to eat, breathing heavily and behaving very differently, then I'd suggest medicating with Waterlife Myxazin or eSHa 2000 in a quarantine tank if you have one plus a filter that you can transfer some existing/established filter media into. Only fill it as much as is required to cover the filter - that way, if buoyancy starts to become a problem (eg sinking like a lead balloon to the bottom or floating up like a helium balloon to the top), then he doesn't have so far to swim up/down.

Best of luck and keep us posted on how he is.

Pics not great, he is sulking down there! You can see his tummy sticks out downwards more than usual and a tummy spread of scales.

Thanks for the advice.
I may change the water a bit again tomorrow - and inc a filter rinse (I have 2 in there). Will pick up some daphnia - have been meaning to get but could never decide whether to get frozen or dried, if one was better or more value than the other.

I don't have a spare heater for quarantine and worry the stress of a move into uncycled fresh tank - even with one of the current filters, would finish him off so will try to avoid.

Unfortunately, he died during the night.
I'm glad he wasn't suffering for a long drawn out period.

I will get some salts in, for future First Aid.
He honestly didn't have any other symptoms and he wasn't really huge at bedtime last night. Inflated but not like some, never saw the scales sticking out at all (just spread a bit like a snake who has just eaten). Had been seen swimming across tank too.

I read gouramis are susceptible to dropsy. Water quality seemed ok to me. Nothing stressful going on in tank - I was keeping an eye on quality as the additional tank mates a month ago needed more food but was trying ensure I didn't over do or anything. (the new tank mates settled in well, no concerns, he wasn't stressed as the corys were downstairs and he was the boss anyway!)

Will miss him as he was the "character" 

Thanks for the advice. Going to improve everybodys diet, and try to increase greenery (Only seem to be able to manage anubias! The twisted leave plant died (2 of)

Very sorry to read about this - he was such an attractive fish too, judging from the photos. It sounds like you've done everything right, though, so try not to berate yourself. It's particularly distressing when there doesn't seem to be a definitive reason as to why a fish falls ill, and particularly when they've otherwise been ok and in fact more so than the other fish. As you say, though, at least he didn't suffer for long which is hopefully of some small consolation.