Re: Lowland Fantasticus and Vanzolinii advice
I keep my vanzos in pairs as they have been shown to be monogamous in the wild. I've also had problems adding adults into established pairs. However, I've seen plenty of examples where groups work. Usually it's frogs that were all raised together or offspring that grow up in viv.
Since vanzolinii Lay in tight holes in the wild, i let mine lay on the glass behind cork slabs. They have laid equally in upside down canisters and horizontal ones on the glass. Face the opening of the canister towards the back of the tank and stick them as far back as possible. This makes the frogs feel more secure. I just let my frogs deposit and raise their own tadpoles. They will raise up to 8 or so Tads at once though I limit it to 6ish. Parent raised froglets morph larger and grow faster in my experience.
For lowlands, and all other fantastica, reduce the light that reaches the bottom of the viv and you will see them more.
I keep all my fantastica types in groups and haven't experienced issues adding extra adults to established groups. A 20 h vert is just fine. My lowlands prefer to lay in the leaf litter or in film canisters in the leaf litter. I face the openings on those to the back as well. I've only heard my males a handful of times.
One thing ive found helpful to catch frogs breeding was putting in a bunch of hidden vertical water holding canisters. Then you can check for tad deposition. Fants are pretty good dropper-offers but they don't feed nutritive eggs.
Hope this helps. I do have extra males if you want to trade I'm off all next week.