Very risky. Normally I would say no, but you have such few fish that you might be able to get away with it. Just add air-stones or something like that before taking away the aeration so that there is as much oxygen in the tank as possible. Plants also generate small amounts of oxygen, so if its a heavily planted tank than it is less risky.
Honestly, I think they'll be perfectly fine, as long as they don't have any other health conditions- I've accidentally left filters off overnight after water changes and I don't run air stones, but my fish came out the other side no worse for wear. To be fair, though, my tank is a lightly stocked 55g. If you're concerned, I'd go with Elkwatcher's idea for the future, but I really don't think one night is going to do them any harm.
A quick note on plants- at night when they're not photosynthesizing, they actually use up oxygen instead of producing it. That's really only a problem if you have a densely planted tank though, if you just have a couple of anubias or something they're not going to suffocate your fish.
I've done it through power outages before. Air it as much as you can by filling up a bucket of aquarium water from the tank and putting it back in right before you go to bed and right when you get up. I read you do that once an hour or so. Buy a battery-operated one off amazon for next time to put your mind at ease.