jdmboy;4393024; said:
yea i was planning on getting 6 or so yo yo loaches. and thats what i was worried about with the cichlids, id end up having a pair and then they might do some damage to other fish in my tank. im still not sure about the silver dollars, idk if they are what i want. i have a feeling that im going to be setting back up the other tanks i have, in order to get all that i want again
Try the bala sharks. They're going to get along well with the loaches and I doubt they will cause any trouble for your BGK if the knife has a cave to hide in. The 125 will hold three bala sharks for a very long time. If the sharks grow too big for the tank, just get rid of them then, but enjoy them in the meantime.
There are also other dither fish you can choose besides bala sharks and silver dollars. You can go for a large shoal of various rainbow fish mixed with giant danios. Rosy barbs also go well with black ghost knives and yo yo loaches and they are very coloful. They get up to about 5 inches, so you can get a dozen or so of those.
I would try to get one large, mid-dwelling fish if you go with the rosy bars or the giant danios/rainbow fish just to have everything swirl around it. Something that grows 8-12 inches and not too aggressive. That is why I was tossing the idea with a severum or geophagus or leopard ctenopoma around. Heck, with a tank like that, you could choose the ctenopoma with the severum or the geophagus with the severum or the ctenopoma with the geophagus or comparable cichlids. A 125 with a catfish, 6 yo yo loaches, a BGK, 2 cichlids of a different species and a large shoal of rosy barbs or a mixed shoal of rainbow fish and/or giant danios sounds like a nice filled out tank to me.
Okay, I just remembered that you wanted to do something other than cichlids. lol. Scratch the severum and geophagus ideas.

You might want to try researching mildly aggressive oddball fish like the leopard ctenopoma that grow in the 8-12 inch range and choose one or two different fish. You showed interest in bichirs earlier. A delhezi bichir and leopard ctenopoma would be two good oddballs to finish the tank with.
1 BGK
1 Leopard Ctenopoma
1 Delhezi Bichir
6 yo yo loaches
A large assortment of giant danios and rainbow fish
Anyway, let us know what you decide. There are any number of ways you can take this. The black ghost knife, yo yo loaches and catfish is a very good start!