Hello, I'm not new to saltwater..I had a 55 gallon for several years with several fish, anemone, etc and no issues. But when I left for college I took the 55 gal. down and bought a little 6 gallon tank used. The tank came with live rock and sand. Everything was fine for a while until i lost time and interest due to school. Well one year later I'm in a new apartment and am trying to resurrect everything.

The tank was sitting with 3 gallons of stagnant water for a year. I cleaned everything out and put the sand/rock in a bucket with no water for about a week before transporting it. Now at my apartment i set everything up and put a damsel in it to restart the nitrogen cycle that i assume had been broken after all of this time.

Well, within a week the damsel has died for no apparent reason. It may have been the stress or temperature (i bought a heater now but it was 72 degrees). In that week i had replaced a gallon of water about every three days. I don't have an ammonia tester and do not know how much i should trust the test strips i have for nitrate and nitrite but i am getting readings of both. I have used two different types of pH test strips and they both read about 7.8.

My questions are plainly what should i do? I am going to bring a sample of water to the aquarium store to get analyzed but how should i start the nitrogen cycle on this tank? Is it possible the bacteria is still alive in the sand? I and i have a partial cycle started? Im sorry, but im so confused and have never really had trouble keeping fish alive in a tank until i downsized to this one. Thanks for any advice or input (sorry for the long post too)

The fact that a Damsel Fish died indicates there is simething wrong with your tank. Your temp is too low. should be above 76. Your ph is too low, should be above 8.0. What is your spec gravity? It should be above 1.20. Your tank is small so things can go bad fast.

I know its too cold, like i said i put a heater in last night, water temps fine now (76-77), i think the temps may have been the stressor that killed the damsel, would you agree?

Spec. gravity is fine, it had been between 1.021-1.023 all week. I also know the pH isnt where it should be, but during the nitrogen cycle doesnt it drop a bit also, and 7.8 shouldnt cause a damsel to die, should it? ..I still dont see how i already have nitrites and nitrates since the tank was shut down for a year w/ stagnant water, then the sand and rock were left out of water for a week. That must be some tough bacteria if the readings are accurate.. Thanks for your help!

If the rock didn't dry out there may have been some bacteria left. So as not to kill more fish finish off with a 'fishless cycle'. Remember your tank is really small so stock must be chosen carefully, the majority of fish at your LFS won't be suitable. A tank that size is quite tricky and requires lots of research to get right.

Thanks Snail. I checked my nitrates with two different tests and they both read 20. I changed out two gallons while trying to vacuum up the gravell as good as i could. A few hours later its still reading 20..But i will finish the cycle up fishless. Like every nano tank my eventual goal would be a little clown w/ an anemone. What do you think, would you advise against that?

Just my opinion, but a 6g isn't big enough for anything except for gobies and firefish. Tough to keep water conditions good enough for an anemone in a nano. Not impossible, but more trouble than it's worth.

If it was me, I'd just strip the tank down and start over, and cycle it fishless. That tank was dead if it was sitting without an ammonia source for a year. Cycling with damsels is done all the time (not my choice, but hey... it's done) but not all damsels make it through it.