Ok- you have a few issues here. 80l is only @21galllons- with 2 fancies plus additional fish, you are overstocked. Fancies need 20gal for the first fish, atleast 10g for each fish after. They are extremely messy fish & need heavy filtration & frequent water changes. You also mentioned your tank is uncycled- you need to test your water daily & do water changes to keep toxins under control. Heres a link on cycling with fish: I just learned about cycling but I already have fish. What now?!
Do you have an API fw
test kit? If you dont, you need to get one asap. Water quality is a likely culprit in your fish's condition though it may not be the only culprit. What you are seeing is dropsy- its a symptom & not an actual disease itself. As your fish is already pineconing, his chances of recovery are not optimistic.
The best thing you called do right now (and in the future) are water changes. I would do a 50% wc
with properly conditioned, temperature-matched water immediately. Add a low dose of aquarium salt (1 tablsp/10g) premixed in a cup tank water & added gradually over the course of 24hrs. Redose only the salt you remove with wcs- ie 50%wc
, redose 1/2 the original amount of salt. Because we do not know what your exact water parameters are, i would continue to do 50% wcs daily until you can get a test kit to monitor your water conditions. I would offer some cooked, deshelled crushed peas as well. If your fish is suffering unduly, euthanasia may be your only option. I wish you luck & hope he recovers with healthy water!