NitrAte question

[mamaber]

This is probably a question only a newbie would ask, but I'm gonna ask it anyway. I've had my 29 gal tank set up for about 2 or 3 months now. I do water changes twice a week and test it regularly. I was out of town for nearly three weeks over the holidays. My husband was still home for two of the three weeks and took care of the fish. As soon as I left, the fish started dying. I taught him how to clean the tank and when and how much to feed the fish. He called me each time another one died. Each time he would test the water and the parameters would be normal. He cleaned the tank like I taught him. When he joined me on our vacation my in laws took over the care. Since it was only a week, I just had them feed the fish. I figured one week w/o cleaning the tank wouldn't hurt. When I got back, only two fish remained. Since then, my nitrAtes are a little high, but the nitrites are at 0. Any ideas what killed my fish? The remaining two are healthy as ever. Why would cause my nitrAtres to be high, but not the nitrItes?
Thanks!
Amber

[Christine]

Cycling your tank causes that. You want nitrItes to be 0. If its not 0 then your tank isnt finished cycling. NitrAtes is the end of line so to speak for the cycle. They are removed by water changes. Fish -> Ammonia -> Nitrite -> Nitrate -> Water change.

[emc7]

Your pet sitters overfed your fish-its a rule--pet sitters always overfeed fish. The excess food caused a brief ammonia surge, also called a mini-cycle, because there was more waste than your bioload was accustomed to. The ammonia was enough to kill a fish, which caused more ammonia, etc. The bioload caught up to the excess ammonia within a day or two and the levels went back down before the test. The end result is higher nitrate which is the least toxic of the three. Cleaning the filters and the gravel because of the death may wash away bacteria and make the problem worse. The proper response to a dead fish is to change large amounts of water and leave the filter alone. Unless your fish are really young, you might be better off just not feeding them for a week.

[Sable]

Indeed; most fish (except fry and some delicate species) are fine without food for anywhere between a week and a month (some species, even longer).

However, you mention your husband knew how to care for the fish and some still died. It's possible that they were diseased; check your living fish for symptoms such as lethargy, loss of appetite, flashing, rapid gill movement, white poops, swollen gills, swollen eyes, white spots or fuzz, and torn fins.

[Mazzy]

The tank was set up for 2-3 months so you know for sure it went through a full cycle in the first place? If not, then it was just finishing the job so-to-speak. Just curious since you said you do water changes twice a week. I think that's a lot personnally but whatever works for you.
As long as the tank was fully ccled in the first place then I'd agree that your fish were overfed. But if you didn't let it go through a full cycle in the beginning then I'd say that's what happened now and the two remaining fish were your most hardy fish so they survived it.

[mamaber]

Thanks for all your help. I imagine overfeeding is what caused the problem. The tank was fully cycled before I left. Interesting how something as simple as overfeeding could cause so much trouble. The remaining two are eating fine and are as active as ever. I see no signs of any problems. In fact one is very close to dropping fry. I'm letting them be for another week or two to make sure there are no other problems. Then I'll consider getting them some new tank mates.

If cleaning the tank/doing water changes twice a week is too often, how often should I be doing them?

Thanks,
Amber

[Mazzy]

better to err on the side of too many than not enough. I'm sure your fish like the clean water. It just seems like a lot of work I usually only do water changes every two weeks - depending on the type of fish and size of the tank of course (with the ray I used to do about 10% everyday after feeding and I fed twice a day! ugh!) but with a regular community tank that isn't overstocked you could cut it to once a week or, with only two in the tank, you could do it even less right now. But that's just my opinion.
In a well stocked 29G I'd do once a week but in an understocked 29, you can save yourself some of that work and go once every two weeks, or, for as long as you only have two in the tank, it will hurt nothing to go every three weeks or even once a month - but that's just cuz there's only two fish in the tank right now. I don't know what your regular stocking is like. HOnestly, fi it were me, I'd only change the water once a month while there's two in there - but I'm kinda lazy