Hey folks, I'm taking my first overnight trip aboard the Captain John out of Galvenston in January. They supply squid only, and I have heard that I should buy other types of bait myself. I would appreciate any advice on what and how much to buy. These trips bottom fish in the daytime and tuna fish at night.
Thanks

squid is good, especially if it's free.
otherwise, if you can carry on a minnow bucket,
spend afew hours after dark catching piggy perch
at the dock. if you catch a couple blackfins, cut 1 up into chunks for nighttime yellowfins. also net up any flying fish
around the boat. Stick a hook in 'em = TUNA CRACK!!!
good luck & welcome to the TFF!
post a report when you get back!

Buy some diamond jigs. search hammered diamond jigs on e-bay then buy the ones from Cape May Tackle: called CM 220 or go to academy and buy some chrome diamond jigs. Having different sizes will allow you adjust to the current. Then let out 200-400 feet of line. most times the fish will hit the jig on the drop, so pay attention to your reel when letting out line. If it stops taking line, you probably got a fish or a hit. If they don't hit it on the drop then stop letting out line when your reel is half-full or empty whatever. Reel up as fast as you can, and you will catch plenty of Blackfin. Slow down and use more motion for yellowfin.

+1 on the diamond jigs. Only other bait I could suggest is a pack of ribbonfish for king mackerel. You can pick them up at one of the bait camps as you get to the island. Otherwise, the squid will work quite well for daytime fishing & the above advice from lite-liner regarding the use of a cut up blackfin for yellowfin bait is spot on!