Theres no shortage of fluorescent colors in catfishing gear, with most only glowing above water helping to detect strikes or ad to the glow show. Firefly coin sinkers utilize the most advanced U.V reactive polymers to not only glow when exposed to black lights but  charge and continue to glow underwater. This glow attracts small baitfish which draw larger predatory fish. So whether fishing at night or during the day at depths where light levels are low firefly sinkers can help draw fish to your baits. 
(Brightness & duration of glow are determined by length & intensity of U.V exposure)