Will baby corydoras survive for a few weeks on live daphnia/pond microfauna?

[PapaverSomniferum]

Closed down our aquarium three weeks ago, rehoming our remaining fish (four adult pepper corydoras). The following week I gave away all the equipment... filter, heater, food, tapsafe etc.

A week after that, with the aquarium still full of water (hadn't got round to draining it), my daughter piped up 'ooh look, there are cory eggs on the glass'. Couldn't see any fry, although there were some microscopic things that looked like pond cyclops (seemed weird, but I did put some daphnia from the pond in there aeons ago, before I read that that was a bad idea, so figured some may have survived). I added a bowl of pond water and some silt, just in case, and kept studying it for signs of life. No sign of corys, just lots of daphnia etc. Figured the eggs didn't hatch.

Until a couple of days ago, when DD brightly calls 'ooh look, corys!'. Yup, two tiny little fish.

So, whilst they grow big enough for me to catch and rehome, will they be ok in an unfiltered tank, living on pond life? It's a 64L tank, and they're absolutely minute, so I can't see that they'd be producing much waste. I'd put some oxygenating plants in with the pond water, so that should help, and I'll put some more microfauna-laden pond water in there today. I'm assuming they'll get what they need from rootling around in the silt and catching daphnia etc?