I have a salt water tank (33G) we put substrate and let it run for a while then started adding rock, this all took about a month. Then we put in Ocellaris Clownfish, that is their real names but people call them false perculas. We never had to put in other fish to break the tank in because of the live rock which has bugs and other ocean stuff on it. Saltwater tanks are expensive and addicting, I spent about 2000 on my 33G in the first year and I love to buy new stuff for it. Don't get a sea urchin they eat everything and will eat all the plant life of your rocks including stuff you paid a lot for from the petstore, get snails to clean your tank without eating valuable plants and corals.