http://tpwd.texas.gov/publications/pwdpubs/media/pwd_bk_l2000_0014.pdf22
Texas Water Safety Act
§ 31.064. Lights
A vessel or motorboat when not at dock must have and exhibit at least one
bright light, lantern, or flashlight from sunset to sunrise in all weather. A vessel
or motorboat when underway between sunset and sunrise in all weather must have
and exhibit the lights prescribed by the commandant of the Coast Guard for boats
of its class. No other lights that may be mistaken for those prescribed may be
exhibited.
this link has the verbiage and diagrams.
http://tpwd.texas.gov/fishboat/boat/safety/vessel_requirements/