Hi
59 litres isn't a lot of gallons - only about 15. That's just to warn you that you shouldn't get any more top-dwelling fish (such as these gouramies) or you'll over-crowd. The pair you have should be ok permanently provided they have plenty of places to hide. Gouramies like these appreciate floating plants and males are territorial so he may chase the female around a bit (which is somewhat stressful for her and another good reason to have plenty of retreats available).
Depending on what kind of molly you have (there are 2 right?), they can easily get to 4". If you go by the 'inch per gallon guideline' - 4" + 4" + 2" + 2" = 12 gallons (which pretty much renders you fully stocked). The extra 3 gallons are best left until you are certain the mollies are fully grown (as some do get to 6") and to allow the tank to mature and stabilize before placing strain on your biological filtration. You probably know all this already but it doesn't hurt to be told twice.
Mollies also don't usualy like gouramies much but, as long as you don't add any more and overcrowd as a result, they should work out ok together.
Anyway, to answer your question. I call the feelers 'feelers' as well (obviously).

In reality they are modified ventral fins that are adapted to exploring a murky environment. They are even covered in taste cells which literally allow the fish to taste whatever it touches. Missing feelers are common because their thread-like - almost 'wormy' - appearance seems to make them irrisistably tempting for some fish. They are also easily trapped in ornaments, cut on sharp corners or caught by a powerful filter. Having said that, feelers that have recently come off should be monitored (the wound that is - not the missing feeler

) as this area can sometimes get infected if the fish is stressed or water quality is poor. Usualy the fish is fine and the feeler soon grows back - though not always to the same length as the original one. Provided your tank is cycled, your fish compatible and your water quality good, this fish (as long as it's healthy and stress-free) should grow back its feeler and be perfectly normal again in time.
