Stumped

DecTenToo

100 l planted tank (aqua nano)
Stable plant growth
Ammonia 0, Nitrite 0, Nitrate 0 using API freshwater kit

History - bad nitrite spike causing loss of a number of fish 4 months ago. Kept it to survivors (3 Bronze corydoras, 2 cardinal tetras and 2 cherry barb). Had a snail outbreak so got 2 assassin snails which seem to be reproducing and I’m now at 10.

Last week decided to take on some more stock as chemistry had been stable for 3 months, namely 5 cardinals and 2 ottos.

One week later 3 of the cardinals and 1 otto gone.

On the cardinals tails appear to be eaten and they ended up tail end in the filter input. Otto was small so not sure about that one.

3 corys, 2 barbs and remaining tetras look healthy and are moving around the tank.

Daily chemistry checks show the same results.

Can anyone suggest where I’m going wrong with stock and any possible problems?

I have no idea.

BigAl81

What kind of filter do you have in the tank? How often do you do water changes and how much do you change?

DecTenToo

Bio filter only (carbon, eheim coarse/medium/fine, biomax rings) and initial polyfilter with weekly 10% water changes ...

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DecTenToo wrote: »

Bio filter only (carbon, eheim coarse/medium/fine, biomax rings) and initial polyfilter with weekly 10% water changes ...

Do bigger water changes. 10 l a week won't make any difference to the quality.

DecTenToo

Thanks. Will do and will monitor for a few weeks.

The Pheasant2

Probably not the case but dead/decaying snails can produce some seriously toxic substances which effectively poison the tank - if you've that many assassins keep an eye out that one of them might not be dead and rotting somewhere in the tank.

DecTenToo

Good point on the snails. I'll do a count/cleanup over the weekend.

Thanks

Berserker

Any update on this OP? Is you nitrate level still at 0? That doesn't sound right to me.

penev10

If your water parameters are OK then personally I'd just put the deaths down to poor livestock.

Cardinals in my experience are very weak. Otos can starve out also. The nipped fins were possibly nipped after death although barbs can be aggro especially if they're not in a larger school.

I think if you got another 4 barbs and brought your scool of cardinals to 10 there should be no aggression. Your stocking level would be fine also if it's a planted tank.

Berserker

penev10 wrote: »

If your water parameters are OK then personally I'd just put the deaths down to poor livestock.

The poster's water parameters are Ammonia 0, Nitrite 0, Nitrate 0. That doesn't sound right to me for a cycled, planted tank. I would expect Ammonia 0, Nitrite 0, Nitrate > 0.

penev10

Berserker wrote: »

The poster's water parameters are Ammonia 0, Nitrite 0, Nitrate 0. That doesn't sound right to me for a cycled, planted tank. I would expect Ammonia 0, Nitrite 0, Nitrate > 0.

Is it not possible in an understocked tank that the plants are consuming all of the nitrates? Especially if the OP is using a fertiliser without nitrogen. I've never had 0 NO3 myself.

DecTenToo

Thanks all

Will be buying a new test kit to be on the safe side and will report back

Stock seems to have been the problem as the original inhabitants are fine.

Berserker

penev10 wrote: »

Is it not possible in an understocked tank that the plants are consuming all of the nitrates? Especially if the OP is using a fertiliser without nitrogen. I've never had 0 NO3 myself.

It is possible technically, I suppose but I've near seen or heard of it happening in reality.

DecTenToo wrote: »

Thanks all

Will be buying a new test kit to be on the safe side and will report back

Stock seems to have been the problem as the original inhabitants are fine.

I see that you are based in Dublin. Not sure where your LFS is but some stores will test your water for you. Seahorse in Ballymount will do it.

Nick Park

Berserker wrote: »

see that you are based in Dublin. Not sure where your LFS is but some stores will test your water for you. Seahorse in Ballymount will do it.

My local Equipet store is always happy to test my water for me. It is sort of surprising that they do so without any requirement that you buy anything.

lynchie

Berserker wrote: »

It is possible technically, I suppose but I've near seen or heard of it happening in reality.

.

I had it happen to me two months back though maybe not understocked as such.

Moved to a bigger tank and added 3 large amazon swords / some crypts / anubias / java fern. Tank has roughly 50 fish (incl. snails / shrimp) so was producing a decent level of No3. Think with a combination of the newer LED lights, the plants were consuming all the nitrates. Started noticing green Cynobacteria growing on the sand which after reading was due to low nitrates. Tested and found I had a 0 / 0 / 0 which was unusual. Now dosing macros (NPK) three times a week to keep my No3 ~10ppm. Cynobacteria has not come back after I removed it. May end up moving to high tech and injection co2 as I'm already dosing ferts now.

Berserker

Nick Park wrote: »

My local Equipet store is always happy to test my water for me. It is sort of surprising that they do so without any requirement that you buy anything.

Yeah, they tend use the water testing to get you in the door.

Sleepy

I've had a tank run at 0 nitrate for years, it was quite lightly stocked, heavily planted and received weekly 20% water changes with the only real dosing being a CO2 injector system.

Rather than relying on in-store testing which will only be done with test kits similar to your own, you could pick up one of the Trition test kits in Seahorse and send it off for full lab testing https://www.triton-lab.de/en/

I tend to do it once or twice a year for my marine system and to say it's comprehensive is an understatement: it picked up problematic trace elements I'd never even heard of at the time (Molybdenum in my case).