I use Corydorus erhardti in my Uruguayan tanks, remained with balzani without a problem.

as you can see even these juvie erhardti are not bothered by the Gymnos, the bolzano are not fish predators, they prefer tiny foods, like most Geophagines.
If the pikes are small enough when first added, they prefer insect prey.
I got these wild caught Crenicichla saxatillus from Ken Davis who takes groups to Uruguay to collect a couple times per year. You might check with him about other appropriate cats (fishfarm.com I believe) is a very good guy to work with.

youngsters above, adult below


as you can see even these juvie erhardti are not bothered by the Gymnos, the bolzano are not fish predators, they prefer tiny foods, like most Geophagines.
If the pikes are small enough when first added, they prefer insect prey.
I got these wild caught Crenicichla saxatillus from Ken Davis who takes groups to Uruguay to collect a couple times per year. You might check with him about other appropriate cats (fishfarm.com I believe) is a very good guy to work with.

youngsters above, adult below







