Help: need BW tankmates

[tbone13]

Hi....I'm new here (and I did read the FAQ's), so excuse my ignorance.
I have a small problem I need some educated advise with. First my tanks quick stats:

55g bow-front
Filtration: Rena Filstar xP2 canister, 2- Aquaclear 402 powerheads w/undergravel.
SG: 1.005-1.010 *marine salt* (I fluctuate annually)
PH: neutral
Temp: 70-72
Substrate: Med. gravel
Decor: small silk plants, resin corals, large dual urn airation decoration, lava rock (I know this combo is not the ideal Decor but I like the look)
Lighting: standard dual 24" daylight bulbs, 2-1watt moon-beam spotlights (Used most)
Inhabitant: 1 single 8" Columbian shark (6 years old)

My problem is...being from Michigan, BW fishes are extremely hard to come by in my area pet shops (detroit suburbs). I once got my hands on some scats, monos, and an archer.....but they only lasted 6 months before perishing. All other BW varieties I can get are too small and become food for the Columbian.
I currently am growing another Columbian shark in another tank to later join him. (right now he's too small)
I didn't want to risk mail ordering scats and monos due to the costs involved and not knowing if they will live in my tank. If I knew what I was doing wrong with them, I'd certainly try again. Maybe I have too much current for these species??
Are there any other species of fish I could maintain instead? I was looking at Firemouth Cichlids, but am not sure. (I do NOT like puffers..so don't say it)
I am almost ready to convert into SW and try that since my shark naturally migrates into the ocean in the wild.
Any help from you guys would be great!!!

 

[Silver Surfer]

keep the salinity between 1.008 and 1.010


Try getting your hands on some green chromides or orange chromides. They are an asian cichlid and a very nice brackish tank fish that will hold up fine against your columbian. Also try some fan dancer gobies... mine chases my GSP around in terror. Archerfish would also be a great choice. Also I would try to stay around 77-78 degrees.. Your water might be too cold.

my tank

GSP
Fan Dancer Goby
Black Goby
archerfish
mono argenteus
orange chromide
orange spotted chromide
pictus cat

 

[Oddball~]

get datnoids, too. However, the tank may be too small for the 2 sharks alone when they become adults, let alone tankmates.

 

[Silver Surfer]

get datnoids, too. However, the tank may be too small for the 2 sharks alone when they become adults, let alone tankmates.

Datnoids get huge, kinda like a grouper and will eventually require a LARGE tank.

 

[Oddball~]

IF he were willing to upgrade, to say, a 75-85 gallon, then he could have certain species of datnoids. Several species grow to only 14"

 

[tbone13]

Thanks for the advise. I think I'll be OK with 2 columbian sharks as the one I have now is 6 years old and only 8" long. It will take awhile for the other to reach good size. As for tankmates, I have a hard enough time finding normal BW fish, let alone chromides. I'm calling a few LFS to see if they can order some. Also I am ordering rainbow fish. Very colorful, hardy, and do quite well in BW. Thanx