RCS steadily dying off for no reason?

[THQ]

Hi all, I'm new, hailing from Melbourne, Australia and I need your help as expert shrimpkeepers to solve a mystery.  I am a beginner aquarist and this is my first time keeping shrimp, but I believe my approach is scientific and informed.

I have a 5G densely planted all-in-one nano tank with mini-sump system filled with seachem matrix and sponge fitlration but no chemical filtration.  Originally with 15 RCS and 4 otos and what look like quite a few tiny round snails hitchhiking on plants (I picked otos as these as these are the only completely shrimp safe fish apparently).  I have never ever seen otos attack or even be interested in shrimp.  In fact, tiny RCS sometimes crawl over them and they just ignore them.  Tank is 6 months old and was fully fishless cycled and matured with algae prior to drip acclimitization and introduction 4 months ago with no shrimp deaths and only 1 oto death within first few days, leaving 4.  A few berried females gave birth couple months back so I have a fair amount of tiny RCS floating around.

Feeding is zucchini blanched in filtered (RO-like except for fluoride) water, and Azoo Max Breed shrimp food, Hikari mini algae wafers.  Both these specifically say they are good for shrimp, do not have copper in the ingredients breakdown, and are unexpired in sealed packs.

Plants are hardy anubias, java ferns and java moss on driftwood, and 2 amazon swords and a few ?ludwigia planted into the substrate.  Also dreaded duckweed which I scoop out every few days before it covers half the water surface.  Lighting is Aqua One PlantGlo 45 cm RGB LED light with 8 hour split photoperiod per day.  Plenty of surface agitation for oxygenation, no airstone.  No CO2 so no pH crashes.

I have noticed about once a fortnight, there is a mature, well coloured RCS who dies off, with its corpse on the substrate being quickly devoured by the tiny snails.  Doesn't seem to correspond to water changes, fertilizer, feeding, etc.

Fertilizer is API root tabs at the very start (none since) and 1/4 dose API leaf zone monthly.  I double checked and neither of these fertilizers advertise that they contain copper compounds, mainly only iron.  Independent lab testing results from their website reveals API root tabs have 474 mg/Kg Cu and leaf zone 6.3 mg/kg, but both with 0.01 detection limits.  I even took a sample of my tap water to my water authority to have it tested and Cu was 0.01 mg/L, much lower than 2 mg/L safe drinking level.  The root tabs and leaf zone copper, after dilution in tank water is at negligible levels also.

Water parameters are tested weekly and always stable (ph 6.4-6.6, ammo 0, nitrites 0, nitrates 0).   I understand the nitrates being 0 is from very low bioload and densely planted causing 0 nitrogen balance from denitrification.  I follow the instructions on the API liquid test kit to shake nitrate #2 test bottle 2 mins, banging it on table, then the test tube for 1 min.  Test kit not expired, and works well for other tanks.  Temp stable at 27C/81F.  During fortnightly 30% WCs (mainly to replace trace elementrs) I temp match and prime my tap water which is the same parameters apart from pH 7.0.  Once every 3 months or so filter/pump maintenance.

What would be your opinion on why my RCS are dying off?  Remainder of shrimp look relatively healthy.  I understand their lifespan is 1-2 years, but these are dying off within a few months.  Most of these were juveniles when I got them.

Thank you.

[NoGi]

I'm sure someone here will be able to give you some suggestions but I just wanted to pop in and say that this is an excellent example of an informative thread whilst asking a question. It's got a lot of information and pictures to boot. Bloody awesome first post mate.

 

[THQ]

Thank you!  Hopefully wasn't too much information.  Didn't want to bore people to death before they got to the end :)

[jayc]

Hi THQ,

as Nogi mentioned, good information has been provided along with your question.

However, there are a couple of critical water parameters that we still need.

Can you get TDS readings and GH & KH tests done?

What gravel is that? (be very specific if you can, brand, name, etc) Some gravels are claimed to be inert, but actually are not.

Can you get a close up of the shrimp's corpse? Side and top shots. 

Do you see any signs of moulting problems?

[Disciple]

I wanted to also see if you can give us the temperature of your tank? 

[jayc]

7 hours ago, Disciple said:

I wanted to also see if you can give us the temperature of your tank? 

THQ mentioned it is 27deg C stable.

[Disciple]

Whoops my mistake.

4 hours ago, jayc said:

THQ mentioned it is 27deg C stable.

Just out of curiosity, how do you keep it stable at 27 @THQ?

[NoGi]

@THQ when you say sponge filter, you are talking about the one attached to an air pump right? Just wanting to confirm that you have air getting into the tank. Probably totally unrelated to your setup but the last time I had deaths when all the other parameters were ok was when I wasn't getting enough air into the water.

[rawprawn]

I would suggest that as a noob like myself, you are better off with a larger tank like a 3 or 4 footer.

Much more forgiving with your water parameters.

[DemonCat]

19 minutes ago, rawprawn said:

I would suggest that as a noob like myself, you are better off with a larger tank like a 3 or 4 footer.

Much more forgiving with your water parameters.

Amen. I firstly had a 1.5ft tank. I ended up spending way to much time trying to fix this, fix that, balance something else... My shrimp didn't berry up at all and the small bunch of white clouds looked ever so cramped. 

Although I put so much money into the small one, i went out and got a 3 ft tank and have not looked back. Much more stable, can see the growth, much less maintenance required. I was unaware that the smaller the tank, the more difficult when I first got it. 

I lived, and I learnt!

Edited February 4, 2016 by DemonCat

[THQ]

On 2/3/2016 at 0:07 PM, Disciple said:

Whoops my mistake.

Just out of curiosity, how do you keep it stable at 27 @THQ?

Just that it seems to be stable on my internal thermometer whic always reads 26.8-27.2C with my 50W heater.

16 hours ago, NoGi said:

@THQ when you say sponge filter, you are talking about the one attached to an air pump right? Just wanting to confirm that you have air getting into the tank. Probably totally unrelated to your setup but the last time I had deaths when all the other parameters were ok was when I wasn't getting enough air into the water.

Sorry, miscommunication.  Not a sponge filter.  A mini sump with a floss-like material for mechanical filtration (it's like a floossed panel that inserts in the first part of the sump.  There is definitely enough surface water agitation for gas exchange to occur.  Sometimes I wonder if the current is too strong for RCS.  Although mid-bottom, things are calmer.

1 hour ago, rawprawn said:

I would suggest that as a noob like myself, you are better off with a larger tank like a 3 or 4 footer.

Much more forgiving with your water parameters.

I understand what you're saying, but my 6 foot tank is full of cichlids.  I only wanted a nano shrimp tank.  Water parameters seem to be stable every time I measure them.

[Matuva]

Did you do something new compared to your routine? new food? using mosquito repellent?

Edited February 4, 2016 by Matuva