Cliff, the hill country is a special place, with probably the best warmwater fly fishing on the planet, and even our cold tailwater is listed in America's 100 Best trout streams, and rated as the best southern tailwater. Most people don't even see it, because they think the Llano is the hill country, but it's not, that's the high mesa above the hill country. Even the San Gabriel drains all that black-dirt farmland east of Burnet. The hill country is the limestone spring creeks that emerge from the escarpment south of a line from Rock Springs through Mountain Home and Harper and, especially the Edward's Aquifer Recharge Zone.
This is upper Cibolo Creek right below Herff Springs, and 20 mi from my house.
There's an A-strain of endemic bass here, and a few miles from here, the creek disappears into the aquifer, to re-emerge near Schertz.
there are big cichlids here, too
this is the headwater springs of the Guadalupe in Kerr WMA - there are also cichlids here
and the Guadalupe around Center Point - I caught 7 endemic bass in the frame of this photo