WARNING: 1) Only eats live foods 2) VERY VERY VERY SHY, you won't see it if you have a hiding place for him to go! 3) Semi-aggressive :| only to smaller fish like tetras though. Overall it is an awesome fish but it just really doesn't go good with a community tank or an aggressive tank..
Elephant noses need a few things to thrive. 1) acidic water: I keep my PH at 6.6 because of other members of the community, but they would really like it more like 6.4 and you can accomplish this by putting in lots of bog wood in the tank and peat right down in the canister filter. 2) they have very good eyesight in dim/darkness but are almost blind in bright light, which is why they may hide if your tank doesn't have a lot of plants or shelter areas and is very bright. They are nocturnal and may stay more active at night-- though mine is out and about constantly, swimming at the top and all over, he never hides! 3) they can be quite aggressive especially with fish THERE OWN SIZE, especially other elephant nose or other fish that have electricity. The "nose" is an electric organ they use to pulse for food and generally find their way around in the dark, they also use it to check out other fish and tell the sex of their own kind. I have found that they leave smaller fish alone completely, and if a fish is closer to their size they will see them as competition for food. If you want more than one EN or just fish about the same size get at least 6 to diffuse aggression. My red rainbows are pretty big and my EN likes to poke at all of them during feeding. I introduced fully mature lake kutubu rainbows and my EN killed them! when I then added in babies he ignores them completely and as they grow he is still leaving them alone. These are just my own experiences and observations. To help with aggression get your EN after you have an established community of acceptable tank mates (several) and this will help the EN to adjust and not be a dick to newly added fish to HIS territory. It is true that they do not do well with very aggressive fish such as cichlids, mainly because of the way they eat-- which brings us to 4) eating: they do not have to have live but I have never seen mine eat flake. They are carvnivores. He eats frozen brine shrimp and bloodworms with relish, but even tho he is sassy and fiercely wants food the way that he eats makes it easy for other fish to eat all of the food before he can. Their lil mouth is unable to open any wider, and they sort of prod with their nose first to sense each morsel then have to suck it in-- so it has to be small enough to fit. I usually add in thawed and strained frozen food in a couple places to make sure he can find some and actually get some, and then I add some flake so that the other fish get distracted at the top while he trolls for food along the bottom. On another note, they can't eat if something happens to the "nose," so they need a soft substrate so that they do not hurt it. 5) don't get one if your tank isn't at least 4 feet wide. They get big and like to swim a lot, at least at night, and they just need the space to swim. If you want to get more than one, and as I have said then you would be getting like 6, you are going to need a very large tank indeed.