FS/FT Yellow Grouper

HI everyone I bought some Live rock and fish sight unseen from a local guy in Brock for my kids tank I just setup I used sand and water out of my DT. Anyways He through in This yellew grouper 2-3", they get to big for my kids tank 20g and they tend to be a bit preditory. So I thinking if I can get a small gobi or some thing like that in trade or $15.00. The guy paid $23.99 for the grouper not long ago. local pickup I can bring it with us when we go to kelowna but if someone buys it they have to be ready to asept it when we get there.

edit:
I'd even take a pepermint shrimp as the rock I got from this guy has quite a bit of atapsia and some kind if halmedia algea. Good thing the rock was dirt cheep. About 2.50/pound or free if you looked at it this way if I bought everything retail then the fish and rock were free. Because I paid 225 for a Hp meter with temp, a refractometere, a aqua romara skimmer, a new bucket of IO salt, 30- 35 pounds of rock, 4 Dansels (blue with yellow tail) this yellow grouper and a couple of miss items.

edit. I believe this guy ia a yellow pseudochromis/ not a yellow grouper I don't know.
added a photo.

Bill