had to quaratine both dwarf gouramis today. today i noticed that both of them had only about half of thier feelers left and one of them looked like it was "dissolving" away. one of the DG also has a big brown spot on his lower fin. im gonna pic up a med for finrot tomarrow but i really dont think the one with the brown spot is gonna make it thru the nite. so far i dont think it was the dwarf puffer that did the damage because the swordtail still has a full tail but them again he is faster. but there is that brown spot on one of the DG
i kept a figure 8 dwarf puffer with a gold gourami, neon blue dwarf gourami, and a opaline gourami in my tank all at once. the other gourami's the older they get and the bigger they get the more aggression you see. after about 4" they start to get really aggressive towards other gouramis. but in that time i also watched my figure 8 numerous times nip fins on all my fish which also included 4 plecos, 1 common, 1 hifin, 2 rubber lip, albino rainbow shark, regular rainbow shark, and like 12 tiger barbs, albino, regular, green, and platinum green. i also watched him chomp off 4 feelers off the gouramis. there was always damage everyday by him. sad to say but luckily he died shortly later but he was tearing apart my fish. hope this helps. but gouramis as they get older and more mature even if they are raised up together they CAN become very aggressive towards each other and it can get ugly. just like betta's do. same would happen if you mixed a gourami with a betta (but i think that is only certain sexes and how many you have).
and if your gourami goes long enough healthy and not being bothered his feeler will grow back. ive seen this happen a couple times