Today I´ve culled some F1 males from my crossbreed tuxedo endler (hybrid) ♂ x platinum koi guppy ♀. All F1 males are roundtails with the exception of four of them. So, I've dculled those four and put them in my mutt tank after I took some pictures.
And short video of them on the balcony:
And short video of them on the balcony: