Decreasing juvenile mortality

YuccaPatrol · Post by **YuccaPatrol** » Sun Nov 12, 2006 6:46 am

After keeping my Cherries for almost a year, the population reached a stable point and very few young shrimp were surviving to adulthood in my smaller 10 and 15 gallon tanks. I certainly have a large number of shrimp in each of my tanks, but I had hoped to be able to share my shrimp with others once I reached a point that I had a surplus of young shrimp.

I had a 55 gallon tank unused in the basement and set it up a month ago as a large breeder tank. Over the past month, I have moved my best looking females and all nicely colored pregnant females to this new tank as I notice them appearing with eggs.

Now the walls of this new tank are covered with babies since it seems that most of them are surviving in a tank with lots more room. I've just never seen so many babies at one time.

Post by **Mustafa** » Sun Nov 12, 2006 8:02 am

It makes sense that you see so many juveniles in the large tank. The water parameters there are probably much more to their liking than in the small tanks. Shrimp hatchlings are a lot more sensitive to things like *traces* of ammonia and even temporarily higher nitrate levels than the adults. They are the first ones to go if water parameters are not close to optimal.

Newjohn · Post by **Newjohn** » Sun Nov 12, 2006 10:06 am

YuccaPatrol
My 125 was up for RCS about the same time as your 55.
I have notice the same thing. And if I remember collectly, I had a population explosion when I first sat-up my 30 breeder.

As other members have asked the Question, in the past.
Will the population level Out.
I quess this answers there question.

So, I guess the next task will be, to see what the MAX Capacity for any given tank.
And set up a grow out tank.
Before the decline of Offspring survival.
Mustafa

Shrimp hatchlings are a lot more sensitive to things like *traces* of ammonia and even temporarily higher nitrate levels than the adults. They are the first ones to go if water parameters are not close to optimal.

Good observation
John

TKD · Post by **TKD** » Sun Nov 12, 2006 11:24 am

This is why you SELL your shrimp...

You keep getting babies that way.

TKD

Pea-brain · Post by **Pea-brain** » Sun Nov 12, 2006 11:46 am

of course it's only natural that your tanks population will reach a maximum. even without decaying water params it would run out of room.....and more shrimp than water isn't good

well I wish you luck!

ToddnBecka · Post by **ToddnBecka** » Sun Nov 12, 2006 4:58 pm

My 10 gallon tank has been going since last spring, and I still haven't seen any decline in breeding. Actually, there are now more berried females than ever before, since some of the earlier babies have matured. I have been selling off the good-sized young shrimp, to make room for the new arrivals to have growing space. I have removed a couple hundred young shrimp that were close to breeding size, but even that many didn't have any effect on the reproduction rate (before removal).

Newjohn · Post by **Newjohn** » Sun Nov 12, 2006 5:21 pm

ToddnBecka
It is all a % thing.
Lets say a 10 Gal.

If you start a Tank with 5 Adult Females, and each hatch out 20 Young.
You will get 100 offspring every 6 to 8 weeks.

After the Tank has been going for awhile.
And say, you have 15 Adult Females hatching out the same 20 Young.
The % of young that will make it to Adult, will decrease.

The fact that the water conditions might not be to there liking, due to the amount of food fed for the number of Shrimp
Or
The competition for the food that is fed.

Just My Thoughts
John

Neonshrimp · Post by **Neonshrimp** » Sun Nov 12, 2006 11:40 pm

So, I guess the next task will be, to see what the MAX Capacity for any given tank.
And set up a grow out tank.
Before the decline of Offspring survival.

This would be good to know, but filtration and water changes would help to increase the MAX Capacity of a tank.

bjar · Post by **bjar** » Mon Nov 13, 2006 1:07 pm

I think the reason for the decline in surviving shrimp usualy is due to "ower grazing" by the adult shrimps ,the shimp fry is probably much more dependant on the "natural" food produced in the thank than adult
shrimp.If you have a large population of adults they will probably also
disturb fry that are molting or just resting wich can´t be good for survival
either.

Fry survival can probably be improved to some degree by giving them more of their own micro habitat like adding pices of things like hamburger
filter mat to the tank .

Neonshrimp · Post by **Neonshrimp** » Tue Nov 14, 2006 12:14 am

Fry survival can probably be improved to some degree by giving them more of their own micro habitat like adding pices of things like hamburger
filter mat to the tank .

I have added oak leaves to promote microorganisms for the babies. How has the hamburger filter mat been working for you?

bjar · Post by **bjar** » Tue Nov 14, 2006 12:53 am

Oak leaf will increase the general production of micro organism in the tank ,but in a highly populated tank the subadults and adults can still "ower graze" what the leavs produce.

I have seen some good results in a friends tank but have yet to try it my self. It is a pitty they don´t make the hamburger mat in green instead of
that ugly blue colour.