Eggs of Caridina sp. Tiger and N. denticulata

[Jan]

Hello,

I have a question. Do mothers of Caridina sp. Tiger and N. denticulata sinensis carry eggs for all their development? I seem the animals release eggs after about two weeks of their development and babies maybe hatch from bottom without any contact with mother. The problem is I have uncovered bottom without any substrate and animals maybe eat eggs before the eggs finish their development.

[GunmetalBlue]

Do mothers of Caridina sp. Tiger and N. denticulata sinensis carry eggs for all their development?

Hi Jan, the answer to that is yes. The eggs are fully developed while on the swimmerettes (takes a little longer than 2 weeks though) and don't spend any time on the floor developing. If an egg is just lying on the floor for a length of time without opening up into a shrimplet, it's likely not alive, or at least, will not survive, so they very well may get eaten.

But you needn't worry with healthy newborn shrimplets, they are fully capable of jumping away, and their parents will not harm them.

-GB

[Jan]

I thank you GunmetalBlue for your reply, but my present impression is still as I wrote. Females release middle developed eggs and before they finish their development they are eaten by adults. I will test it now. I will give females with eggs to a special tank with grid instead of bottom. So I will prevent them and other specimens to feed on eggs. I have the same experience with C. japonica. Females carry eggs about one month after they release them. It lasts about two or three weeks, it is not at a stroke! Eggs develop on bottom usually from one day to two weeks than larvae hatch. In the meantime they are completly eaten by adults. I must separate female with eggs to special tank to prevent in any contact of females with released eggs!!

[GunmetalBlue]

Feel free to perform your experiment and please do let of know of your findings.

> "Eggs develop on bottom usually from one day to two weeks than larvae hatch."

Originally you were talking about Tigers and N. denticulata sinensis. Those do not hatch as larvae. They hatch as shrimplets (if carried to term) and I can assure you, if they are healthy they easily escape getting eaten by their adults.

Now if you refer to C. japonica, they DO hatch as larvae, however, no matter how successful your grid experiment, they would not survive due to the fact that C. japonica larvae need brackish/salt water to survive before they can eventually metamorph into shrimplets.

There is a reason Tigers and N. denticulata sinensis carry eggs to term. They need to aerate, keep them clean and protect them. If your Tigers and N. denticulata sinensis are releasing eggs long before it is time for for them to hatch, the eggs lose out on the care needed for them to hatch successfully into shrimplets and most likely will get covered with fungus and/or microorganism will feed on them and destroy them.

If you are looking forward to your Tigers and N. denticulata sinensis having shrimplets but they are not successfully carrying the eggs to term, I would probably also suggest spending some time trying to figure out the cause, ie. lack of fertilization, stress, unfavorable water conditions, etc.

-GB

[Jan]

OK thanks

I rear three shrimp species just now – Tigers, N. denticulata sinensis and C. japonica. Every species has special tank building only for them without any other organisms as fish, molluscs atc. Inner equipment consist from filtration, piece of wood, slate stones as a refuge, plant Valisneria dubiana, fallen beech leaves. I clean tanks regularly and guard temperature, pH, hardness and concentration of nitrogen compounds. I have not any problem with any rearing species. I know Tigers and N. denticulata sinensis have direct development without larval stage in their development and C. japonica has indirect development with larval stage in their life cycle.

Problem about Tigers and N. denticulata sinensis is in big disproportion in number of eggs of females and number of shrimplets. I never saw released eggs and dead shrimplets. Filtration is secured before shrimplets. As you wrote, problem is maybe in fertilisation. Males have low fecundity or they do not copulate.

I rear C. japonica about one years. I know famous internet websites about rearing of larval stage, but my success is still low. I try it breed about four months yet. Mortality is about 95% during larval stage . I rear them in 34 ppm salinity, temperature about 24 °C, light and dark is 12 : 12 hours, I feed them the way I scrape walls and bottom of tank and disperse scraped materials in water. No any other food. I don´t aerate tanks (aeration is not good!!!,but slow movement of water is good). I tried various ways and combination of salinity, food as yeast, live freshwater algae, dried freshwater algae, special food for marine zooplancton and invertebrates as corals and so on, photoperiod, temperature, water change, type of salt, aeration, density of animals, but without any prominent success. I just now prepare special tanks with biological filtration and powerful lights for bigger algae development.

I would like to ask you about your opinion. The famous web sites about breeding C. japonica recommend permanent light without any dark. If you light off, larvae die. Is it cause low oxigen concentration during night? They often feed larvae by live algae (green water). Are algae possigle to exhaust oxigen under critical concentration for larvae?

[GunmetalBlue]

Hi Jan, there's a current discussion on experiences breeding Amanos (C. japonica) here:
viewtopic.php?t=1011if

You could try copying and pasting your last two paragraphs and posting it there - hopefully they can offer you opinion/advice on breeding C. japonica.

-GB