search for royal blue instead of "blacklight" ... another keyword would be dental blue. Actinic is another good keyword

edit examples:

https://www.amazon.com/LEDENET-Waterproof-Aquarium-Aluminum-Lighting/dp/B09YPZ4LT7?th=1

https://www.bulkreefsupply.com/blue-lumi-lite-strip-led-reef-brite.html