Elephant noses are VERY long-lived. I have a pair that is 18 years old. I inherited them about 6 months ago from a lady that kept them in a 30g tank their whole life. Thank God she did lots of water changes! At 1st, they swam in my tank in a little 30g circle. They are out & about all the time now in my 125g tank & they love it! Their main diet is blackworms but they eat anything I put in their tank, including freeze-dried plankton, small pieces of shrimp & even flakes. I think their varied taste must have to do with the competition of other fish in that tank--all aggressive eaters.
They are really tough & very friendly towards the other fish. I have a fairly aggressive tank, with a frontosa that killed a pleco once, a 12" very aggressive goldspot pleco & even a fahaka puffer. I've caught them playing with pieces of plants, like a porpoise with a ball or something--very cute. I know it has been said that you should either keep 1, 3 or more but these 2 fellas only squabble a little, so I can't say otherwise on that subject. They are around 8-9" ea. They are out all the time but so are my clown loaches. This has to do with supplying them with a lot of cover. It makes them feel more secure, knowing there is somewhere to go if need be.