have you done SW before? .. the overhead on a properly set-up SW tank can be alot more and the upkeep itself more costly. in a 55 a snowflake eel should be fine. But unless you intend to go with one of the small lionfish specimines they will need an upgrade eventually as well. I would also consider a 75 over a 55 for the added width of the tank. It can make a big difference in the long-run. and I completely disagree with Mandarin fish.. while very attractively colored lil' fish they need a well established reef system to thrive in, unless you get very very lucky to get one that readily accepts flakes which ime a majority do not.
SW - snowflake and a fuzzy dwarf lion ( or similar dwarf species, fuzzys are one of my personal favorites)
FW - arrowana's particularly silvers (largest species) would be okay in all likely hood for 12-18 monthes in a 75 then would need an upgrade.. and the bigger the better. once the fish hits the width of the tank it's time for an upgrade. they will grow 1"+ a month. though there are certaintly other species that could also fit this "monster bill" dpending on your preferences.. particularly why you like the arrowanas to begin with that may be more in a size range thats more feasable.
well thanks then i think my decision is made
