My nitrates are sky high and my fish are dying [sad]

[DangerousMouse]

I don't know why, the levels have been good for a while...

Am I going to lose all my fish?

I am newbie fish owner but guess you should probably do water changes while you work out whats going wrong. How big is tank? How long have you had it? How many fish? Have you got plants?

If all was ok before what's changed? Did your filter stop working or did you put something in the water that killed off your bacteria. We had lots of probs when first started as couldn't get rid of the chlorine in our tap water so filter didn't grow any bacteria but subsequently its been fine.

I expect someone more knowledgeable will come along soon but can feel your pain at the HUGE responsibility of fish keeping.

Yeah, I've been doing a third water change every second day and it's still reading as high nitrate! Its a 3 foot tank, I don't know how many litres, but it's not overstocked (especially not now!) I've got a dozen or so small community fish.

Thats the thing - nothing changed at all.. I've had the set up since around xmas, been slowly adding the fish, had some fry which are in a seperate nursery tank now, got live plants and a decent filter..

I've had a consistant problem with leeches in the tank, but they are at bay by keeping the water slightly salted and I only see the odd small one when I use the gravel vacuum, but I've had this problem a while and they don't affect the fish at all.

I'd be doing at least a half change every day or twice a day whilst you get the levels under control.

If nothing has really changed then there must have been a dead fish or lots of uneaten food causing a problem.

Flatworms normally appear if you're overfeeding, how much food are they getting? Could any of your DCs be feeding the fish when you're not looking? Have you tested your tap water nitrate?

Other water readings and a livestock list would really help.

After testing this morning the nitrates are back to 0, so thats good news, I'll continue with the daily water changes as there was a dead fish this morning and 2 look like they will die soon

They definatley haven't been overfed, they get a small pinch every other day and some blood worms once a week instead of flakes, DD knows the importance of this and I'm sure she hasn't been feeding them, my other tanks aren't affected by this and are thriving.

Hopefully now the nitrates are back down things will be okay and once the remaining ill fish have died I wont lose any more.

Water readings are back to normal now, and I have 4 platies, 3 endlers, 3 guppies, pleco, 3 danios, 2 swordtails and a few fry which have escaped being transfered to the nursery tank. I think it is 180 litres capacity.

Doesn't sound overstocked- what sort of plec is it?

NitrAte should not be zero- what are the other readings? Did you test your tap water nitrate?

My plec is about 2 inches long, so not a large one (yet)

My tap water Nitrate (not nitrite) is 0 and the tank water is definatley still reading 0.

Ph 6.6
KH 100
GH 250 - maybe slightly lower
nitrate 0
nitrite 0

No more dead fish today, but my 2 ill ones still look ill, I guess it's good that the others still seem ok.

Just done the ammonia and that is 0

Those readings are weird- ammonia, nitrite and nitrate would only all be zero in an empty tank. Also pretty rare to have zero nitrate in tap water. What test kit are you using? If you loik on your water company website it might tell you the estimated nitrate level.

Ammonia and nitrites should always be zero because you should have enough bacteria to cope with stable levels of feeding and stocking. If you add more fish you might get a slight increase in ammonia and nitrites while bacteria increase to cope with an increased load. If this had happened I could understand why there was a sudden increase in nitrates. The nitrates have to come from somewhere. My only thought is that something went wrong temporarily at the water company's end and there was an influx of nitrates in the tap water which has now been dealt with (hence the return to normal levels in your tap water now and the recovery of the tank water). My nitrate levels are close to zero because the tank plants use most of it up, but it isn't usually the case that nitrates are at zero (and they don't need to be - as long as they are kept low by plants or water changes).

It's a king British test kit, little strips you dip in the water. I can't explain the results, they just are! It's good my tank is looking better now anyway, thanks for all your input. I think maybe I had a dead fish somewhere and that caused it, who knows?!

I believe the strip kits are pretty poor. I would suggest the API version, PaH do the individual tests for 10 quid and you get about 180 teats per pack.