care of Eels?

Hi. Some weeks ago I stopped at a pet store where they had a pair of
beautiful eels. Their colours were similar to the Chain Eel (Echidna
catenata) and the Honeycomb Moray (Gymnothorax favagineus). They were around
1.5 m, so I doubt it was the first specie. But judging from the pics I found
online it's neither the second. They were mostly white, with few retics
(sp?) on the head that diminuished towards the end of the body. Are there
other similar species?

We have a huge aquarium at home, aprox. 150x80x80 cm, now inhabited by 2
red-bellied and 4 normal piranhas. I thought once they are death, between
2-3 years I think (they are 7 and 8 years now, one of the big guys died last
month), I'd like to try with one of these eels. I know that the maintenance
of a marine aquarium is much higher than the one we have right now. I made a
research about eels in internet, but found only a few indications:
- carnivore
- peeks out of tank (that's funny
- needs hides
- needs clean water

That isn't very much. Does anyone here keep any of this fishes and can give
me some advise? I.e. How much they eat at each meal and how often, if they
need UV-light, other special things to care about? I don't know much about
sal****er fishes, so I though I may get some informations right now. I have
a friend who has been in breeding fishes (beta splendens and others) for
years and can surely help me with the tecnical part (filtration, etc), but
he never kept eels nor does he know about their care.

Every helpful advice is greatly appreciated.

Anna