Perhaps it was a bowfin (called a grinnel in TX). I caught one in the San Jacinto River once. I cut this out from the link below: "The ability to breathe air is attained early in life and is used most frequently at night and when water temperature is high, coinciding with periods of greatest activity. The bowfin is able to survive prolonged air breathing periods. Young bowfin have been observed surviving for 21 days in a pond with no standing water. "
http://www.vernonweb.com/bowfin.htm
Read the comments section by people that have caught them and you'll see a lot of them are in TX, and they also relate their tendancy to come up out of the water. Neat fish, over 150 million years old.