Was fishing yesterday at Squaw and my buddy hooks into some brush. He pulls it all the way to the boat and then unhooks it. A small white looking creature falls off on the rail and starts moving. We bend over for a closer look and it looked just like a crab about the size of a shirt button. It was raining, so by the time I started reaching for my phone to take a picture It scurried off the edge of the boat and I didn't get a picture. Anybody ever seen a crab in freshwater?

When I was a kid we would go catfishing below the lake Houston dam on the san jacinto river and many times reeled in blue crabs but that river runs into the gulf not too far away

I have had fish spit some up at texoma don't have a pic though.

I'd never seen or heard of them. But a quick search turned up this...the more you know.
http://texasfishingforum.com/forums/ubbthreads.php/topics/5889549/Freshwater_Crabs

I do know my ex wife used to fish it a lot back in the 80's, so it is not surprising.

I've caught 2 blue crabs in Nasworthy and I know a guy that used to catch one or two a month on trot lines there believe it or not. I eventually took one of them to the TPWD and they told me they got in when they used to stock the redfish. Apparently before they dredged the lake it was fairly common to catch them.

Hubbard Creek is full of them.

Whitney is full of them

Ive seen some on retainer walls at Granbury the size of your hand.

I've seen them in whitney and my son had found them under rocks there as well. I thought I had pictures but can't find them.

Harris Mud Crabs

Have also seen them in the Brazos below PK Dam

I see them in the Brazos below Whitney when they let out water. There can be 100s at times.