I just used dirty tank water and some gravel in my plastic tub for a week while the filter took the beneficial bacteria in the water and gravel. Insta-cycle.
If you set one up now with a sponge filter running in the main tank you'd have one when needed....and with livebearers you'll be using it a lot.
For example, mosquitofish, which are sort of like half-sized endlers, breed so fast that many places have started banning them. Australia has had issues with imported mosquitofish eating all the killifish eggs and endangering species.
Edit: With your tank though, there's really no need. It looks like you got more plant than fish in that tank.