But the OP doesn't have an established (biological) filter.
People who apparently despise planted cycling (not yourself, I hasten to add), fail to realise that plants do not need to be firmly rooted and established, in order to do their thing. As long as they're alive, they'll do good for the tank and the faster growing the plant, the more good it'll do.
In emergencies, floating plants and/or even basic elodea pondweed will make a positive impact.
Please understand that nitrites, like ammonia, will burn the skin of the fish and, perhaps more importantly, their gills. Whilst both can recover, gills are more fragile and could be less effective, post-recovery.
Daily water changes might be necessary, or less, depending upon the nitrite levels...ideally, you're aiming for zero readings. What
@Fishmanic suggests is helpful.
Whilst the plastic plants are not ideal for the purposes of cycling and water health, they
will provide surfaces for beneficial bacteria to grow on, which is a Good Thing.
(They also offer some security, although their harder plastic nature will make them less safe in a fish-dashing emergency).