Nitrites are not toxic to saltwater fish at the levels we could/would achieve, it would take nitrites in the 100s of ppm to be toxic. Having had freshwater aquariums all my life and my last saltwater stint from '99-2010 coming back in '21ish this was a hard thing for me to grasp also. I am still decided on the cycle needs to be complete before I add stuff but its no longer about if nitrite will harm my inhabitants its more about seeing the cycle established. I am willing to wait I am not in a hurry. The base fact here that I think you may be getting hung up on is the same with people using API test kits, that .25 is probably an inaccuracy in the test itself and even if it is .25 or less that is also not toxic. I guess op could do a nitrite test just to see if there is nitrite present even though it would not matter. Time the tank has been running and the fact they used ammonia and bacteria to start the tank means its cycled at least to a safe enough point to add fish. Adding fish now will increase the biome, gut bacteria from the fish will help the process.Jeez, are you brandon with a different acc? (where is brandon btw, did I miss some major drama while I was away in the last couple of years).
Cycling is finished when nitrites are converting to nitrates. Most of fishkeepers and every single bottled bacteria manufacturers thinks this way, thats why their product contains bacteria to convert nitrites as well.
There are many studies out there about nitrite toxicity, its definitely not beneficial for fish in higher concentrations, if these are too high level for some, there is dr tims article for beginners, mentions nitrites a few times: https://www.drtimsaquatics.com/resources/fishless-cycling/







