Hello, I set up a 15g nano tank last week to hold two fish sent by my son (firefish and a neon goby). I used two pieces of live rock that I purchased plus a sponge from my established 45g. 50% water from established tank and 50% new water The LFS said I could put the two fish in right away. They seem fine but I am worried about an ammonia spike. I also put in Cycle bacteria and Dr Tim’s. Should I do water changes with water from my main tank? What else can I do to keep the fish alive?