Small update :
The tapole is devoloping his back leggs. It's also getting lighter in color, it's seems like he is changing color.
After some research and allot of going back and forth, I bought an Arcadia ProT5 UVB 6% lamp. For some (not all!!!) Histrionica I've seen enough evidence that proofs these frogs benefits from UV(b).
I highly recomend NOT using UVB lamps for other frogs tho!
There is allot of opinions and disccusion on the use of UV(b) for Histionica and the use of UV(b) varies a lot between breeders. Some use it 14hours a day, some 6, some 2 others only 10 minutes... My common sense tells me to follow the breeders that use it 2 hours a day @ noon, when the sun is the most bright... They also got the best result in my research. The breeders that use it for only 10minutes a day were very close second!
The lamp I use only shines over one half of the tank, so the frogs can hide easy from the UV(b). So far I havent seem the take a sunbath, but it only has been 5 days since I started using the lamp.