Rainbow trout in Texas…yes, you read that correctly. For largemouth and smallmouth bass, minimum length limit = 14 inches. All these streams are rather small, which is the main reason why the bass don’t grow large – there simply is not enough of an ecosystem to support a larger fish. The upper run of the Guadalupe River holds good populations of Guadalupe Bass, Smallmouth Bass, Largemouth Bass, Rio Grande Cichlids, Pan fish, and multiple species of Carp. The Guadalupe Bass is also not a very popular fish as it is restricted to the Edwards Plateau, Guadalupe, San Antonio and the upper Nueces river drainages found in southern Texas. Below the Canyon Lake Dam is where the tail race of the Guadalupe River is formed, and where our guided fly fishing … Due to the lower flows, water temperatures below Canyon Dam are elevated. On the upside, the lake is close to full and a couple of good rains this fall might give us some nice flows by December. While bass and sunfish are still present the real draw for most fly fishers is the year-round population of rainbow trout! The word for the Guadalupe in Summer 2020 is “hot.” Inflow and outflow at Canyon Lake are currently below average for this time of year. Fishing Regulations for Guadalupe River. To combat the spread of invasive zebra mussels, the law requires draining of water from boats and onboard receptacles when leaving or approaching public fresh waters.. Black bass.