Sand seatrout (Cynoscion arenarius ) is of commercial and recreational importance to the Gulf states. Spawning behavior, feeding habits, length-weight relationships and standard length-total length relationships were determined for 498 sand seatrout collected between May 1966 and March 1968 from Galveston and Trinity Bays, Texas and from the Gulf of Mexico near Galveston Island. Sand seatrout distribution, gonadal development and the time young-of-the-year appeared in estuaries indicated that this species spawns near Gulf-to-bay passes in the Gulf of Mexico between March and Aug with a spawning peak during spring. Fish and crustaceans dominated the diet of sand seatrout, crustaceans occurred more frequently in fish <160 mm SL and fish predominated in those >160 mm SL. The length-weight regressions derived from 267 sand seatrout 125-375 mm SL differed between sexes. The standard length-total length relationship was TL = 0.7 + 1.1 SL