i think its normal... my red betta who I had for a 6 months now (yay!) has two white tips at the bottom of his two fins right below his "gills" ( u know, the thing that opens when bettas flares... I forget wat its called) i seen it there on him (firefly) since I bought him from the store.... he also has translucent black ends of his fins, but when I researched it, this means that he is still growing (?). The white tip, in my eyes is actually more white/ neon green. And I think that's normal... my firefly is very healthy and swims around alot... he jumps when he knows its feeding time. haha... i think as long as your betta's fin looks okay... like its not shredded, one of my bettas has either fin rot, or the plastic plants are shredding it, which I removed immediately when I saw this. g'luck!