Mvande6; I have several clients in Brazoria Co who were flooded earlier this month. Oddly enough, it didn't rain all that much in their area, but the Brazos River's watershed in Central Texas brought a LOT of water downstream that simply couldn't discharge into the Gulf fast enough.
Depending on the distance from the Gulf, there's no telling what you witnessed in your pond - but I'd guess it was a flathead catfish.