High Ammonia - Everything dying...except one?

Rule #1... Cure the tank with either live rock (at least 1/2 lb per gallon for curing is ideal, IMO), or use deli shrimp (or pure ammonia) and let it cycle until everything falls to zero. This gives you a much larger population of bacteria for breaking down the ammonia your fish produce, which gives wiggle room as you figure stuff out. If you use fish to cycle, you torture some fish and only get enough bacteria for those exact fish. Cycling with fish kills or makes sick all but the toughest fish. (You've already got damsels in there, so you may need to tough it out or move them to a quarantine tank while you do a full cycle.)

Rule #2: Add no more than two fish per month. This is because it takes a little while for the bacteria colonies to adjust to the additional ammonia from new fish. If you add fish too fast, you cycle your tank again. Remember the part about this killing fish?

Rule #3: If at all possible quarantine your fish for at least four weeks before adding them to your main tank. This way, one sick fish doesn't kill the majority of your fish. Almost all parasites can be killed by a 10 minute dip in pH adjusted freshwater and 6 weeks of 1.009 hyposalinity quarantine.

Rule #4: Know your fish. Damsels are highly territorial and often kill clownfish and other damsels. If you are going to have peaceful fish with more aggressive fish, make sure the peaceful fish have some time to get comfortable with your tank before adding the more aggressive ones.

Rule #5: If something is wrong, do water changes frequently. If you're having major problems (like disease outbreak) you can do 10% water changes every day to keep your fish from stressing out and getting sicker.

The feeding sounds like you are doing it right. A lot of fish store and marine aquarium books skip the months of time you should have a marine tank set up before you add fish or hurry you through adding the fish.

Another factor to check is to make sure you have calibrated your hydrometer. (Have someone else or your fish store compare its results to a refractometer's if you aren't using a refractometer.)

Right now, it sounds like your tank is cycling, as I assume you meant ammonia, not pH.

Another thing to point out is, if you cant keep fish alive in there, you wont be able to keep an anemone in there, they are alot easier to kill and harder to take care of then a clown fish, and anemones require matured aquariums..

Dave,

Most fish can live in serious polution for a little while, but the pollution was getting steadily worse as the days passed. The four types of fish you described are also some of the toughest reef fish in terms of surviving bad water quality. It's sort of like how we would go if living in a house slowly being filled with methane gas over a course of months (ignoring the fact that the house would blow up every time somebody turned on a light ).

If you want a place for the clownfish to live, you are better off buying a fake anenome than a real one, because it won't die and fill your tank with ammonia. I'm of the opinion that nobody should buy a sea anenome until they've kept fish, mushroom corals, button polyps, and large polyp stony corals alive for at least a year. They live hundreds of years in the wild and average six months in fish tanks.

Damsels are every bit as immune to real anenomes as clownfish, so a real one would not be much protection. Clownfish, in fact, are damselfish and all damselfish have the anenome immunity. Clownfish are just slower and not very vicious as damsels go, so many of the other damsels can kill them, just like they kill any damsel that invades their territory. Tanks full of damselfish work on the principle that they are all too tough and established to get killed by each other. Damselfish are known to attack sharks, so they're pretty much the wolverines of the reef world: fearless, mean, and tougher than almost anything else their size (except mantis shrimp, but that's a whole different issue).

Cycling a tank generally takes 1-3 months to complete properly. Those containers of bacteria might knock a week or two off the process, but they really are not as good as they claim. If you are going to use the deli shrimp, I strongly recommend getting the damsels out of there, as a true cycle first sends your ammonia off the chart, then your nitrite, then finally the nitrate before they all settle down to near-zero values.

If you don't have anywhere to put the damsels, just do water changes pretty frequently and the tank will go through a small cycle. Then you should only add one fish per month, so that you don't trigger another cycle, or purposely overfeed the tank a little after it is cycled with the damsels, so that the excess food will feed the bacteria. You don't want to overfeed much, though, or you could get too much toxin in there for the fish.