Wipe Out

[dw1305]

Hi all,

Sorry to resurect but i needed a thread to say that i've had a similar wipe out, but i dont think its down to plants its down to a dead zebra snail that i did not remove..

Quite likely unfortunately, once the Zebra Nerite had died, the bacterial decomposition of its proteins would:

1. liberate ammonia (NH3), and
2. cause a bacterial bloom.

As well as the direct toxicity of the ammonia (which may be pH dependent, NH3 is more toxic at higher pH than the ammonium ion NH4+), and the oxygen use by the increased bacterial bioload, you would also get oxygen depletion as more NH4+ entered biological filtration. The number to make the equation balance are a bit strange, but

55NH4+ + 76 O2 + 109HCO3- > C5H7O2N + 54NO2-+ 57H2O + 104H2CO3 and that NO2 (nitrite) is then converted to NO3 (nitrate): 400NO2- + NH4+ + 4H2CO3 + HCO3- + 195 O2 > C5H7O2N + 3H2O + 400 NO3-

If the water becomes oxygen depleted further deaths are inevitable, decomposition then leads to more ammonia which leads to a larger demand for oxygen and more fish/shrimp deaths etc until the water is totally de-oxygenated and everything dies. Low oxygen would have killed the fish/shrimps even if the ammonia didn't.

I'm not convinced that snails like Zebra Nerites are sustainable in most tanks long term, unless you have hard, high conductivity water and a calcium source (cuttle-bone etc) <http://www.planetinverts.com/zebra_nerite_snail.html>.

cheers Darrel

 

[nayr88]

Sad the hear mate 🙁

Good bit of info there DW really indepth! What is cuttle bone? Is it something you can place in the tank? How does this effect shrimp?

 

[Westyggx]

Thanks Darrel I thought it may have been the cause. Gutted I had them since babies since August and just got them to reproduce some off spring.

 

[dw1305]

Hi all,

What is cuttle bone? Is it something you can place in the tank? How does this effect shrimp?

It is a spongy mollusc shell, the internal "skeleton" of the Cuttle-fish (a Cephalopod Mollusc). You can buy them really cheaply, because people use them as a calcium source for Budgies and Canaries etc. <http://en.wikipedia.org/wiki/Cuttlebone>.

The Nerite would graze on it and get calcium, but because the "bone" is both soft and the aragonite form of calcium carbonate it will raise dKH.

If you had a shrimp which needed soft water it is probably incompatible with the Zebra Nerite long term.

I can keep MTS in all my tanks, but they show a lot of shell attrition in the older shell whorls. Ramshorns just about hang on in some of the tanks, but have fragile white shells, and all the other snails I've tried (like Assassin Snails), didn't last at all.

cheers Darrel

 

[Radik]

The only way to counteract this is to have plenty of shrimp who will pick up on dead snail later on. As Darrel said, nerites are worst for any CRS tank. Ramshorn, assasins are not happy in CRS water. Although assasins will last quite long. Trumpets are probably one of best they even breed in CRS water. Pest snails have no problem multiply as usual.

 

[Westyggx]

The only way to counteract this is to have plenty of shrimp who will pick up on dead snail later on. As Darrel said, nerites are worst for any CRS tank. Ramshorn, assasins are not happy in CRS water. Although assasins will last quite long. Trumpets are probably one of best they even breed in CRS water. Pest snails have no problem multiply as usual.

I have plenty of Cherry shrimp probably 50+ as well as CRS and they ate the snail remains. It was probably not eaten fast enough though?

 

[Radik]

CRS is more sensitive than cherry they are pond shrimp vs fresh stream shrimp.

 

[dw1305]

Hi all,

I have plenty of Cherry shrimp probably 50+ as well as CRS and they ate the snail remains. It was probably not eaten fast enough though?

It may not matter whether the shrimps ate the dead Nerite or not. Whilst them eating it was a preferable action in terms of water quality, if you were close to the carrying capacity of the tank, even the increased NH3 production from the gills of the shrimp (NH3 will diffuse out along its concentration gradient with the water continually from the shrimps gills, in exactly the same way it would from a fishes) caused by the break-down of the extra protein may have been enough to compromise water quality (either by lower oxygen levels or toxic NH3 levels) and start the high NH3 > low O2 cycle > shrimp death > high NH3 > low O2.... cycle.

This is partially why I like a lot of floating plants (or emergent plants), because floating plants like Limnobium, or emergents like Cyperus, have access to aerial CO2 (and O2) they can respond to a sudden increase in nitrogen levels by increasing growth. This gives you a lot of "spare" filtration capacity in case of accident. The same applies to keeping O2 levels high, filtration systems which maximise gas exchange and dissolved O2 (like "wet and dry" trickle filters) gives you extra biological filtration capacity when you need it.

Biological filtration is really all about oxygen, this is why aquatic biologists look at the Biochemical Oxygen Demand (BOD) as the most important measure of water pollution. Rapidly growing plants reduce the BOD by removing NH3 and NO2 before they enter microbial nitrification, and by supplying oxygen during photosynthesis, and if you can supply enough oxygen even sudden large increases in BOD (like a undiscovered death) need not be fatal for the other tank inhabitants.

I think this one should be available <Aquatic phytoremediation: novel insights in tropical and subtropical regions> <http://195.37.231.82/publications/pac/pdf/2010/pdf/8201x0027.pdf>

cheers Darrel