It's just fine If you can get a little closer to 80, that would also be good. Do you have an Ace Hardware store near you? They have a pure ammonia dilution (no surfactants, etc.) that I've found useful for fish less cycling. You can get a bacteria colony larger that way than with fish food. If not, no worries! Just add one or two fish at a time when the cycle is done and wait for the bacteria to build up before adding more.