The Yerbalitos are a pretty fish, but like most Gymnos they require a cool-down period in the winter or they will waste away. They need a few months of an unheated tank down into the 60s or so. I'm told they are also prone to HITH, even with good water quality.
I actually removed my EB acaras from my 150 community and put them in a 55 for a few weeks to let them calm down and pair off in a more quiet tank. Then I moved the rest back to the 150.
Dwarf pikes definitely love wrigglers/free-swimming fry for snacks. Better pull the spawn after all if you can. The nice thing about acaras is that they'll spawn frequently from now until the end of time, now that they've paired. So if this doesn't work out, there'll be more soon.