OOoops I totally forgot to add conditioner to water in buckets before I added it back into the 55 gallon aquarium. I went back 20 minutes later and added it into tank. Will fish be okay? I have three fancy tailed goldfish and a mystery snail.
The fish will be fine. The conditioner neutralizes chlorine/chloramine, which can kill beneficial bacterial colonies in high doses. As long as you didn't do a massive (50%) water change, all should be fine for your fish and your filters.