# RCS disappearing without a trace!



## Nat N (Jun 6, 2010)

Hi everyone,
I hope somebody can shed some light on this. I have a very successful little low tech tank, denseley planted. In fact, I had it posted on this forum a while ago with photos. It now happenned for the second time and I am really puzzeled by this. A thriving population of RCS dissapeared without a trace - e.g. no dead bodies whatsoever. Both times the population is growing, seems to be happy with plenty of them out and about and small shrimps seen - and then I see fewer and fewer of them within a couple of weeks. I have not seen any dead shrimps and everything within the tank is the same as previously...
Tank stats:
30 litres (24 litres of water)
PH - 7.4
KH - 6
GH - 9
Phosphates - 1.5 ppm
Nitrates - 10 ppm
Plants: Crypt Beckettii, Pogostemon Helferi, Eleocharis Parvula, Arthraxon (Sphaerocaryum Malacense) - which replaced Cyperus about 6 weeks ago and recently added Hydrocotyle Sibthorpioides.
Light - 24 watts
Ferts - mostly none, an occasional dose of a pre-mixed off the shelf one every few weeks with half a dose. 
Other inhabitants: 5 White Cloud Mountain Monnows, two Amanos and one Sewellia sp.
Any thoughts?
Thanks in advance.
Edit: forgot to add that the filtration is with an external smallest Hydor with glassware and the temp is about 20 C.


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## TAB (Feb 7, 2009)

Could be the white clouds are just eating the young and the old are just dieing off. the swellia can also be guilty.


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## Newt (Apr 1, 2004)

If your not using a sponge over the filter intake look inside your filter.

I also think they may be getting eaten by your fish.


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## Nat N (Jun 6, 2010)

I also suspect that the Minnows might be to blame. However, the fact that the shrimps were multiplying and thriving first puzzles me. When I re-started the colony last May, I added about 40-50 shrimps from different sources. In July I had so many babies there that a dozen of shrimp from this tank were transferred to another one to start a new colony there. By September this tank was literally "bursting" with shrimps - adults and juveniles. They were everywhere in great numbers. By mid December there is almost none left: I could see 4 after half an hour searching. As I said, I never saw any dead shripms. The fish in the tank are the same for the whole time. 
I know about the filter: I kept on finding baby shrimps in there - all alive and well. I did change the intake of the filter and now they do not get sucked in there. 
By the way, the "daughter" colony in another tank is doing well - living with Threadfin Rainbows and Harlequin Rasboras - there are many many of the shrimps seen around.... I never heard about Minnows being a threat to the shrimps (at least not to adults which are three quaters of the size of the Minnows) and the Sewellia has a type of mouth which is probably not designed to eat anything else but auswuchs in the tank...
I did another seach on the internet... nope... nothing about Minnows eating adult shrimps... Honestly, I cannot think of anything else...


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## Newt (Apr 1, 2004)

I always wondered if the Amanos are the culprit as I have had this issue from time to time in my 10 gallon shrimp tank with CRS and Orange bee shrimp dissappearing but never all of the RCS. They are quite agressive. I watched a standoff over a piece of food in my 75 between a huge Amano and an RCS. Guess who got the food.


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## Nat N (Jun 6, 2010)

I agree that Amanos are aggressive. It also could be that the Minnows were praying on the youngsters... With the Christmas/New Year break, I had time to search the Net and although I did not find any definate answers, I read a whole lot of similar stories like mine. I now think that this is probably a combination of a few unfortunate factors - Amanos, Minnows, and possibly something else (which I fail to identify). I have the impression that RCS are extremely hardy. Last year, I removed the riccia which I had in this tank and unsure if I wanted it for somewhere else, put it in a small tub in the concervatory. To be honest, I forgot about it untill a few months later... On inspection, the riccia was all mixed up with the thread algae and all other possible algae in that tub - and there were a few alive and well Cherries there! They were obviously trapped in the riccia when they were babies and they have grown to healthy adults without filters, food, any care from my part whatsoever - in an unheated concervatory over winter! So, I can only be guessing that something in the tank water was disagreing with them and the weakened ones were taken out by the Amanos and the Minnows but it must be something which is worse than the conditions of that forgotten tub... 
I am not going to do this straight away but closer to spring I will replace the Minnows with something like Celestial Pearl Danios or Emerald eye Rasboras. The Minnows will be advertised for free to a good home locally and the Amanos will go to one of my other tanks to join the ones already living there. Then I will start again with the RCS and see what happens...


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## frroK (May 9, 2011)

Similar thing is happening to me at the moment. But I actually saw my amano eating a shrimp! It most likely dead or dying though. I have no adult shrimps left. Not really sure what happened either. I have 3 black bar Endler's in this tank as well. Never once saw them eating any shrimp. They pretty much leave them alone. I planning on moving my amano shrimp into another tank. They too aggressive and steal the food from the cherries.


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## Nat N (Jun 6, 2010)

Your Endlers are definately not able to eat adult shrimps - they are even smaller than the Minnows. With all things taken into consideration - Amanos being agreesive and the possibility of some even small fish (like my Minnows) harassing and praying on shrimp babies - there is one very interesting opinion on the subject I was offered on another forum. That is that in my particular case I may have fallen victim of my own initial success with RCS. It was suggested that too many shrimps may be the cause of the problem. RCS as small shrimps do not have a reputation of being a big bio load. However, exceeding a sertain optimum number of them could be the cause of some pathogens accumulating in a tank which will start killing them! 
I thought this was an interesting suggestion to consider. It definately explains the disappearance of the adults (probably eaten after death by the live ones and by other tank mates).
So, I thought I would share this opinion as it seems quite logical to me. Getting rid of the pathogens before re-introducing new batch of shrimp may be vital. Seachem Paraguard was suggested for the purpose.


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## DrEd (May 5, 2009)

My amano even captured & ate a few of my cardinal tetras. I didn't believed it when my daughter told me the first time. Then I was really shocked when I actually saw it. I feed the shrimps every 2 days. Maybe they are too hungry?

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