Cherry Shrimp Breeding But No Young Survive.

[DanDare]

Hi all,

I'm hoping someone out there can offer some advice.

I have a 112 L, heavily planted (vallis, java moss, java fern), mature (8 years) shrimp only aquarium.
It was previously a community fish tank, and at one time, I had breeding cherry shrimp in with the fish.

I moved all the fish into a larger aquarium and intended to keep the smaller one as a shrimp colony, only moving shrimp into the community tank once they'd reached a certain size (my Apisto's will demolish anything they can fit in their mouths). The only other critters in the shrimp tank are some small snails that came with the plants, and these weird grey worm like things, but they're only 1cm long and move so slowly I doubt they could catch young shrimp.

I have at least 15 cherry shrimp of different age, sex, size and grade. I purchased them in batches from three different sources, at different times.

They all seem happy enough, they're bright, out in the open, and I regularly see berried females. The trouble is, I never see any juveniles and the population isn't increasing.

I have a internal pump with the inlet mounted high, pushing water through a hood mounted canister filter and back in using a spray bar. I've checked the filter and it's not full of shrimp. Nor should that account for 100% of the young disappearing.

I don't do much maintenance on the tank since the bio-load is negligible. I remove algae and replace evaporated water, but otherwise it's stable.

I feed them roughly once a week, and then it's just some blanched veg or some shrimp pellets.

There's no metal in the tank. Only gravel, rock and wood (none changed since the tank was cycled).

My LFS suggested I try increasing the population, but that doesn't seem worth while as they are obviously breeding. They also suggested a supplement for juveniles, so I've started adding a bit of Bacter AE.

Water parameters as follows:
Temp: 24C
PH: 7.5 (I'm attempting to lower this a bit using Almond leaves)
Ammonia: 0
Nitrites: 0
Nitrates: 0
Alkalinity: 4dH
Hardness: 8dH

Apologies for the long post but I'm stumped.

Thanks

 

[Demeter32]

In all honestly this seems odd to me. The only thing that I can think of is the water is too soft.

Take a look at this: http://www.thekrib.com/Plants/CO2/khgh.html

I'm not totally fluent in the whole hardness and pH stuff, but your water seems to be on the soft side. Shrimp generally need a decent amount of dissolved minerals in the water to allow proper molting and shrimplet development. Maybe there is enough minerals for the adults but the little ones with the faster growth rate and increased need for minerals might not be holding out. The website I added states that some species may live/ "adapt" to different hardness and pH but they may not be able to breed.

I've a colony of shrimp in a pH of 7.8-8 with relatively hard water and the shrimplets are doing well. No problems with molting either.

 

[DanDare]

In all honestly this seems odd to me. The only thing that I can think of is the water is too soft.

Take a look at this: http://www.thekrib.com/Plants/CO2/khgh.html

I'm not totally fluent in the whole hardness and pH stuff, but your water seems to be on the soft side. Shrimp generally need a decent amount of dissolved minerals in the water to allow proper molting and shrimplet development. Maybe there is enough minerals for the adults but the little ones with the faster growth rate and increased need for minerals might not be holding out. The website I added states that some species may live/ "adapt" to different hardness and pH but they may not be able to breed.

I've a colony of shrimp in a pH of 7.8-8 with relatively hard water and the shrimplets are doing well. No problems with molting either.

Hi,

Thanks for the quick response.
I know, it's weird right?
Friends of mine, that live within 20 miles from me, successfully breed using treated tap water. And I have in the past.
I have some JBL Aquadur which I use in my larger community tank. I'll try some of that with a 10% water change at a lower temp (I've read that can trigger mating) and hope for the best.
Thanks again. I'll update if there's any progress.

 

[Essjay]

I don't think your water being too soft is the problem. My water parameters are pH 7.5 GH 5 dH and KH 3 dH and I have a thriving colony of red cherry shrimps. When I first got shrimps the problem I had was keeping adults alive. The last one to die was a berried female, and she died as soon as her eggs hatched. My colony grew from those baby shrimps.

There is one difference I can see - from the day they hatched my baby shrimps were fed every day on a tiny pinch of finely crushed Hikari Shrimp Cuisine - I pulverised the pellets with a pestle and mortar.

 

[NickAu]

I have a internal pump with the inlet mounted high

Do you have some sort of filter intake guard?

 

[DanDare]

Do you have some sort of filter intake guard?

Hi,

I don't (except for the snail shells partially blocking it). But it's mounted high and isn't all that powerful.
I just can't believe that it'd suck up all the juveniles for the past year, which is how long this issue has been going on.

I've been adding a few extra shrimp every few months and all those adults thrive. I regularly see at least one berried female but nothing comes of it.

 

[DanDare]

Just to be sure, I've added a sponge to the pumps inlet. So let's wait and see....

 

[thrujenseyes]

That's a head scratcher for sure.
Are you only keeping neocardinia?
Because if you have any ghost shrimp in there they will most certainly eat anything small enough that they can catch. I'm sure an Amano might also.
And if any of your snails are Assassins they too will eat anything they can catch...
Although any one of those three (even all three together) would be very rare to wipe out every stinking baby!