sorry to hear about your gupp... my male tux died last week.. he had the same symptoms. Im not an expert but i wold up teh temp to about 82 (i go to about 81.5) and add aquarium salt... or if you have otehr fish in the tank that are helthy, try diping him in a seprate jar/tank with the salt solution (the stress caused by treatment may kill him so be careful!) if he looks more stressed in the solution place him back in the tank .... it may be flukes making it hard for him to take in oxygen
im not shure if its ok for me to quote this site but here goes......
quoted from
http/www.fishdoc.co.uk/disease/flukes.htm
"''Damage and diagnosis
The fish response to the irritation caused by flukes is similar to any other irritant, whether it is parasites or chemical. Initially there will be rubbing and flashing. As the disease reaches a more advanced stage the fish will become lethargic - which is the point when some people think the problem has gone away. At a very advanced stage the fish will isolate itself and spend long periods laying on the bottom with its fins clamped to its body. Other signs may be skin cloudiness resulting from excess mucus production, skin hyperplasia, or focal reddening. A definite diagnosis can only be made via a skin scrape or gill biopsy. In large numbers, flukes will kill fish either directly, or indirectly through secondary infections.
Treatments
Right from the start let me say that in many cases flukes are hard to treat and complete eradication is virtually impossible. For individuals affected with flukes, consecutive salt baths over 2-3 days can be useful. Using a quaternary ammonium compound in conjunction with, but not at the same time as, salt baths can be useful, in both clearing the skin and gills of excess mucus and debris as well as soothing damaged tissues.
Malachite and formalin is often affective, although my experience is that the stronger dose needs to be used. It most cases, where the flukes are a nuisance rather than a real danger the old M&F will probably suffice.
For all out war, the best treatments are organophosphates such as masoten.
Another promising treatment is high dose, bath treatments with chloramine-T. A few trials I have carried out show that in most cases chloramine-T is quite effective, but it is early days to draw any firm conclusions. The draw-back of bath treatments is that it does mean handling the fish and having a large treatment tank. Due to the complications of using chloramine-T in a typical pond, it is unlikely to be so successful as a pond treatment. Bath treatments also allow the life phases which exist in the ponds (eggs and embryos) to continue to survive. Your freshly "cleaned" individual fish will be returned to a pond with emerging stages in it!
Whilst, with enough determination, beating skin flukes is relatively easy, however, the same can't always be said for gill flukes. Because of gill hyperplasia and increased mucus, the gill-dwellers are often afforded a high degree of protection from chemical treatments. I have had several experiences of flukes surviving multiple treatments safely ensconced in the gill. In such a situation the outlook for the fish is poor, because in addition to the gill flukes there will almost certainly be other gill damage and gill disease.
The most important step in preventing a serious fluke or indeed any parasite problem is first to investigate abnormal behaviour - that is incessant rubbing and flashing or lethargy. Take a scrape and see what's going on. Don't just say "parasites" and dump some chemical into the water. It is important to know what you're dealing with and how severe the problem is. In severe cases it is important to do a follow up at the end of the treatment to see how effective it has been. How severe is severe? One or two flukes in a mucus sample is not abnormal. Any more than that definitely warrants treatment.""""
i hope this helps in the futer but im sorry to say it sounds to me like the fis may have reached the end
BTW: im still battling flukes and ick with my 3 gupp females but i think there gonna pull threw. if you catch any illnes after the first sign you have a better chance at overcoming it... as soon as i see my gups flashing (rubbing on rocks) i start salt treatment, some may think its wrong but it seems to make the fish happier and more active when they get a saltbath at first sign of illness. also when they first get sick they are alot better with dealing with the stress of neting and moving to the salt bath..... just my 2 cents