Certainly you don't have to have them, but if you can afford them - go for it. If you really want an advantage, go for the thru-hull lights.
They attract bait and you'll love what you see at night. Also, and probably my favorite reason to have them is the advantage you get for handling fish at the boat in the dark. Having leadered one over 240, I can tell you they're crazy at the boat and a 4' spear slashing around in the dark could get pretty hairy!
thanks for the info. I don't know that I would want to go all out and buy lights just for swordfishing since I probably won't be targeting them much. I do however have a few starefire bulbs for floundering. Does the color matter or would the white starefires work just as well?
Any light helps bring bait and predators to your boat. I'm assuming your going to try for swords on overnight tuna trips. By hanging the flounder lights off your stern, not only might it attract swords, but it also helps load the livewell with live flyers for the tuna. Don't be hesitant on dropping them down either. Both tuna and swordfish eat them but I don't put them on lines more than 200 feet deep, they don't seem to live well beyond those depths.