Everything's being going along really well with our tropical set up and then one of our two baby mollies was dead at the bottom of the tank on Sunday morning ( fine the previous day) and our two cory cats are spending the majority of their time inside a cave ornament? Up till recently they were either swimming about the bottom, or even up and down the tank on occasion. We're worried about them?

Anyway, way back I remember our LFS saying never to let our nitrate level get above 10?

When we did a weekly water change on sunday the readings were:

PH - btwn 7.4 -7.6
Ammonia - 0
Nitrite - 0
Nitrate - btwn 20 - 50 (its never been that high - red not orange)

180 litre tank - 12 fish so definetely not overstocked ( 5 tetras, 2 gouramis, 1 otocinclus., 2 mollies, 2 cory cats)

A further partial water change on Mon reduced the ph to 7.2 but nitrate remains at 20?

Water change tue and today, and nitrate still at 20? And to try to help also, we've just changed the fine wool pad media in the filter ( Aquis 1000)

I've been looking back at some old posts and looks like you experienced forum members are saying nitrate below 50 is fine? This conflicts with what LFS told us so help - please?

Naturally we're worried that the cory cats are gonna go the same way as baby molly, and god forbid teh others will then start dying/getting ill. If only they could talk and tell us eh?

Can anyone advise please?

MANY THANKS

This post has been edited by fergiesek: Jun 25 2008, 07:58 PM

It is preferable to keep the nitrates as low as possible. If you want to breed fish then try to keep the nitrates below 20ppm but it depends on where you live. In the UK it is common for tap water to have 20 or 30ppm of nitrate in. This means the fish that are bred locally actually breed happily in water with a higher nitrate level. It also means you will never get your nitrates below the levels in the tap water without using reverse osmosis (R/O) or rain water.

It is unlikely that level of nitrate would have killed the molly.

Thanks Colin T,

Firstly my apologies. I think I've confused my question cos I mentioned the baby molly. We're not actually wanting to breed our fish. The babies were a completely happy surprise to us a while back! ( sadly mummy molly and 3 babies died some time ago. daddy and 1 baby are still with us tho thankfully)

So, if we don't want to breed is nitrate of 20 ok?

And can you ( or anyone) suggest why cory cats are hiding away? Strange?

Many thanks again

Anything below 40ppm is fine for most fish. Sensitive fish require nitrates to be kept below 20ppm.

The cories are hiding because there's not enough of them. They're shoaling fish that really need the company of their own kind. I'd recommend getting about 4 more (assuming you have the room)

This post has been edited by TetraLinz: Jun 25 2008, 08:04 PM

Can i ask how long the tank has been set up?
Also are you using liquid or paper strip tests

TetraLinz - that makes sense tho we got the cories mid feb so I wonder why they used to swim about together happily before? Anyway, they are lovely wee fishes so getting some more is a good idea.
Can I be a pain and ask another question. Sensitive fish? Would any of mine be classed as sensitive? Corys. mollies, gouramis, otocinclus, sepae tetras?
Many thanks.

Davo86 - The tanks been set up since January. We use an API Freshwater Master Test Kit. Many thanks

This post has been edited by fergiesek: Jun 25 2008, 08:26 PM

What type of gourami is it? The rest should all be OK

If not looking to breed or keep sencitive species, nitrate upto 400-1000ppm is stated as a "safe" level. You don't want to lower the nitrate too quickly, but jumps of 50 are easily done with healthy fish IME

The API (and most other) nitrate kit is notoriously innaccurate below 50ppm, so take its reading as a guide, not the full truth Ottos are sencitive, but not realy to nitrate as far as I'm aware. For sencitive species, keep nitrate below 100. As a general rule though, the lower the nitrate the healthier the tank

Do you gravel clean, and if so how, and how often?

The corries are hiding as they are being upset by something. What exactly may be hard to pin down, if they were once bold an active, as this makes small group size less likely It could be abnormal noise levels, new tankmates, room furnature change arround right through to bacterial infections..... Absolutely anything. Pinning down a caurse will be hard witout acctually seeing your tank in situe, and having known what the tank and it's surroudings have been like over the last few months...

Do the corries look "normal"? Faster breathing, excess slime, rubbing or laziness noticed?

All the best
Rabbut

Hi TetraLinz,

We've got two blue gouramis.

Thanks

Hi Rabbut,

Thanks for this. Just so I'm sure, as my nitrate on the API test is below 50 now thats ok?

We gravel clean weekly, as well as a weekly water change of 25-30% ( apart from this week where we've done about a 10% water change every night since sunday as I'd mentioned in my first post)

The corys do seem to be out when I go in first thing in the morning ( bout 6:30am) to feed the fish and they scarper into the cave when I approach the tank. Not just me - anyone! ( The room light comes on automatically at just before 6am and the tank light at 6am, Just mentioning in case its relevant Sudden 'shock of the light or whatever.)
Theres' been no changes in furniture, or the tank? I did remove the nursery to let the last baby molly into the main tank but the corys were behaving 'strangely' before that?

When I do get a chance to see them I look at them carefully and no superficial symptoms at all. They do look lazy tho? In mean in comparison to what they were? I'd be grateful for any advice.

Many thanks

This post has been edited by fergiesek: Jun 25 2008, 09:16 PM

The gourami should be OK then I've had a quick look on various sites and there's no mention of nitrate sensitivity on any of them.

http://freshaquarium.about.com/od/gourami/p/bluegourami.htm

All I'm seeing with the way the cories are acting, is flight from the top predator (you) My Blue Ram cichlid does that when I suddenly appear from nowhere - and I've had him since November (atm, he's in a tank on his own, but he'll soon have the company of a shoal of tetras). The cories will be more secure in a shoal.

This post has been edited by TetraLinz: Jun 25 2008, 09:26 PM

That was really thoughtful of you TetraLinz. Thank you.

Great advice from Rabbut!!

As far as i know nitrate is the least likely to cause any damage, in my tank it always seems to be pretty high even the day after my weekly water change.I have gouramis,angelfish,cories etc... and they are all absolutely fine.

How often do you feed your fish?Overfeeding could also be a reason for high levels of nitrate.Also do you have plants in your tank?Dead plant matter if not removed from a tank can decay and raise the nitrate levels in a tank.

Oh and your LFS is talking rubbish,as said high levels of nitrate isn't a problem,it's high levels of nitrite/ammonia that can be toxic to fish!

That's not strictly true. If nitrate gets above 40ppm, it's just as toxic as ammonia and nitrite. Try keeping a sensitive fish like a blue ram in high nitrate - you'll see what I'm talking about.

Rubish. Sorry is that is blunt, but jump into the scientific section and you will eventuallly find a thead on nitrate toxidity, were three of four scientific papers are quoted, giving "safe" levels of nitrate for fish between 400 and 1000ppm, so 50 isn't a problem for most species. Mebers such as Davo keep rams in water with a nitrate level of 50-60ppm, so 40 won't harm them. Nitrate does however indicate levels of other toxins in the water, that we cannont test for. These, TetraLinz, may be affecting your rams, but it won't be the nitrate unless they are wild caught (very unlikely) and even then, they can be aclimated to a higher nitrate reading over time

fergiesek, Nitrate below 50 is fine, so don't worry about it. Just keep up with water changes and it will eventually level out. If it is more than 40ppm above tap water readings though, I'd increase the %age of waterchanges you do each week

All the best
Rabbut

Actually, YOU'RE the one in the wrong, Rabbut. And I didn't mention MY ram. Nitrate level here is 10ppm. My Ram, FYI, is fine. I'm going on the information posted by a MUCH better fishkeeper than you or myself will EVER be. 400-1000ppm nitrate?! ####?! I was hoping that was a typing error. In the UK, the legal limit for tapwater nitrate is 50ppm. Many fish have provably suffered in less nitrate levels than that.

You're going on the information of Scientists?! Meh . . . My information is coming from an ex-animal rescue worker and probably the best fishkeeper in the country.

Thank you all very much for your advice - very much appreciated.

And apologies for starting a lively debate! )

Fergie
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