What would you do with an Empty 55 gal. if you were in my shoes??

thanks for the input thus far, but some folks are asking me what im into, I am asking what YOU would do with the tank if it was yours. Also, if you tell me to do a river setup, let me know what i need to setup something like this (ie, filtration, circulation ideas). I am not a newbie, by any means, nor am I an expert, somewhere inbetween i guess, i worked in two LFS prior to my joining the Coast Guard, perhaps thats why I am having a hard time with this, i have too many ideas, and only one aquarium to execute them on. As far as fish availability, i cant think of anything that i cant get my hands on here, there are a TON of LFS here and they all have a HUGE variety. Thanks again for the help thus far.
 
Loaches and rainbows are well suited to river set up. Put your 2217 intake at the opposite end of the tank to the spray bar. Add a powerhead to increase flow. If you like bubbles you could also put an airwall under the spraybar. You might have to forego the gouramis if you create that much current, though.

Yo yo loaches are quite a bit bigger than Sids.
 
If it was me, I would go one of two ways(both river setups): Congo(Zaire) River setup or maybe an Australian river with Rainbowfish, gudgeons, and not quite sure what else..
 
Don't you have soft water over there in Hawaii? I would exploit that and get fish that thrive in low PH conditions like the Australian river biotype mentioned by Cali. Or you can always go S.American. Might even be able to breed some.
 
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