Survival rate, did you find the cause?

**hyoushoku** · 25th Nov 2014, 09:19 PM

"Maybe sometimes it's: hatch-rate." <---- You are right about this. Usually after shrimp is berried for 2 weeks, you will see a significant number of eggs are reduced. The shrimp will dump those eggs that she think it is not hatching.

Other than this, there is another important stage. The first week after hatch is the critical period. During the first week, they will have their first moult. Once they successfully moulted, they more or less will survive. This is the observation you have about "the number of shrimplets I see after 5 days, that's about 95% of the shrimp that will grow up". I'm not sure what contribute to the survival of first moult.

**ShrimpmasterNL** · 25th Nov 2014, 09:29 PM

It's just a theory, but I'm starting to believe that the period when the female is developing the eggs is far more important than the period when the shrimplets come out of their eggs. The right food and source of vitamins and nutrients. Because when the shrimplet in the egg starts to develop, it can not profit from any source from outside, except from some minerals in the water maybe?
Does this make sense?

**hyoushoku** · 25th Nov 2014, 09:42 PM

Originally Posted by ShrimpmasterNL

It's just a theory, but I'm starting to believe that the period when the female is developing the eggs is far more important than the period when the shrimplets come out of their eggs. The right food and source of vitamins and nutrients. Because when the shrimplet in the egg starts to develop, it can not profit from any source from outside, except from some minerals in the water maybe?
Does this make sense?

Yes, it totally make sense. With enough nutrients provided to the female, she will produce healthier eggs with more nutrients packed in the embryo. This is why you will find new shrimp that berried within short period entering your tank will have much lesser eggs survive till hatch. However when she is berried, the reason she dumped some of the eggs are unknown. I do have the hypothesis as of below:
1. The sperm is not enough or healthy to fertilise all eggs. This is one of the reason why I find that older female loves younger males.
2. Eggs drop when she is trying to swim. If she has good hiding place, she will not be stressed and swimming around once in awhile.
3. Inexperience or sloppy mummy.

Regarding the first moult period, I discovered water flow rate is very critical to Sulawesi shrimplets; they are very bad swimmer and could die swimming too much. However for soft-water shrimp, I'm not sure.

**hyoushoku** · 28th Nov 2014, 10:06 PM

Hi ShrimpmasterNL,

I think I have proven about the nutrients.

Recently, I had revamped a few tanks. One of them is using ADA Amazonia AS and another one is using lava sand. The preparation process of layout material and plant, the cycling method and duration, daily dosing and feeding regime, water nutrition reconstruction and water change process of these two tanks are exactly the same. However in the ADA AS tank, there is massive white worm and cyclop population explosion on week 3 and last till week 5. But the tank with lava sand only have gradual increment of the population and the increment stop at the level similar to matured tank.

In addition, with the exact same water reconstruction method applied, the conductivity of the water in the tank that has ADA AS measured 500uS. But the the conductivity of the water in the tank that has lava sand measured at 400uS. The pH of the water in the tank that has ADA AS drops steadily till pH 5.6. Hence, the delta of the conductivity could be contributed by excess organic acid leeching out from ADA AS. I added aragonite to neutralise the organic acid until pH 6.5 and the conductivity reduced by 50uS. Assuming the neutralisation is 70% effective and aragonite is leeching some stuffs too, there is still quite a significant gap on higher conductivity.

As such, the additional fertiliser and organic matters leeched out by the ADA AS is really nourishing. Which explains why when a new tank is setup, the shrimp will breed extremely fast. This is pretty aligned with why shrimp farmer and hardcore shrimp breeder changes their substrate at least every 6 months.