By far, my favorite fish in the world! I have had 3 of them, but they all have jumped from my tank no matter what type of netting cover I have come up with, so I have not gotten another one. Prices on these guys have come down recently, you shouldn't pay more than $75-$80 for them.
I think a 3.5" sanded would be plenty fine, they make their holes in nooks between rocks and they will use shells and such to build their holes up. Although tanks like Karin's with 6"+ sandbeds are jawfish heaven, most I have seen are happy in tanks with 3" sandbeds.
Mh
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SWA Rookie aka "Ignorance on FIRE!"
Promised son fish, left with SWA BOOK! Wife on-board, son’s attention span has blossomed! Life is GOOD!