I have been in the saltwater hobby nearly a decade and the water cycle hasn't been as big an issue for fish-only setups, which is what you appear to have. I have been able to keep fish alive in setups established just 48hrs. When you do this, you want to minimize bio load in the delicate ecosystem, so keep the following in mind...
1. Ensure you have beneficial bacteria in your system, either through live rock or live sand.
2. While the water params are important, I have gotten away with simply checking the temperature and salinty. For me, the targets are 78-79 degrees and .024 salinity.
3. Ensure a slow acclimation and keep the the aquariums lights off or to a minimal for the first few hours.
4. Make sure there are places for your fish to hide when it finds its home...rocks and such usually do the trick.
5. Finally, insure your system has good water circulation. If you have good water movements, the fish work less to pass water through their gills and stress less.
And for the part that isn't as much your fault, check for quality specimen. At the petshop, make sure the fish looks physically healthy and that it is active. If possible, have an employee feed the fish. I try to avoid fish that have been in captivity less then 10 days -- most saltwater fish come from the wild and are probably still acclimating to captivity, which is not specific to your aquarium.
And if worst comes to worst, try the hardiest of fish first...don't get a blue hippo tang or a lion fish or a clown trigger. Start with a damsel or two. Let the hardier, cheaper fish, break in your aquarium and prepare it for the nicer pricier ones.
Good luck and hope this helps.Saltwater tank done cycled but my fish died n i left it for 5months,can still use the water?help?if you left it alone for 5 months... is there even any water left in it? you'd need to dilute it back to a regular SG and hoppe and pray that the little critter in your live rock and sand didn't die..
refill the tank and wait about 2 weeks if you notice any ammonia building up add a few pounds of fresh live rock and you'll have to re-cycle your tank.. after that treat it as you would any new tank
