Metabetaeus lohena larvae update

[KenCotigirl]

The short version is that I have kept one M. lohena larvae alive for the last 36 hours from 6am Tues to now about 6pm Wed.

Doing a take off of Paul Harvey now for the rest of the story.

Doing a little research it is believed that M. lohena larvae needs full salt water to develop. The advantage of plantonic larvae is that they can colonize new areas far afield by drifting on the currents and feeding on other planton. This would account for the limited yolk sac that Mustafa noticed in the previous pictures. This is opposed to H. rubra which produces a non feeding larvae with a large yolk sac that basically stays where it is released. I could provide the list of references upon request if you wish to read the scientific papers.

With a limited yolk sac in a larvae even for species with an abrieviated time as larvae feeding is a problem. I found an interesting article from this forum about breeding orange shrimp. This article discussed the modified french method for feeding the shrimp larvae. Basically you create a soup of algae to feed the larvae. No other food. Apparently algae is high in proteins. The larvae feeds off the algae and produces waste that feeds the algae. Without any other kinds of feeding you reduce your chances of crashes. The algae still needs the 16 hours of direct light.

Well problem number one. I crashed the algae. Nannochloropsis sp. I did not provide the algae with 16 hours of direct artificial light. I started another batch with good results but not before one female released her larvae. Now for problem number two. The next female dropped her clutch and I missed it. The third female's clutch I would not lose without a fight. I turned off the lights except for a pen light on the tank cover. My previous experience is that the larvae are strongly attracted to the light. I checked on the tank every hour from 8pm to 1am. Unfortunetly I fell asleep and woke up at 6am. The clutch was gone and no larvae to be found. Why didn't I use an alarm to wake myself? I was saved by daylight savings time. It was still fairly dark and after a thorough inspection I found two larvae. I caught one with my turkey baster and transfered it to the algae tank. The other larvae sank to the bottem and could not be found.

I was hoping for thirty maybe twenty or even ten but one is better than naught. I had the day off since I had to go to the dentist. About once a hour I checked on my larvae. By about noon or 6 hours in the algae soup the larvae was not floating but rested on the bottom of the tank. I was sure it was near death. Coming home from the dentist and after some chores I checked on the larvae again about 6pm. It was still alive. I checked again before bed, upon waking and coming home from work today and the larvae was alive and still on the tank bottom.

I am fully prepared for the larvae to be dead by bed time but obviously hope not. My algae soup has a sg of about 1.020+. Temps are room temps about 75 deg. f. 10000k light source inches from tank. Should the larvae die I will use the current protocol again. It seem logical until it fails after several attempts. No pictures available. Very difficult to see let alone film the larvae. Will provide update.

Ken P

[zapisto]

very interesting
Thanks for sharing

[Newjohn]

Thanks for the progress notes.

As for larvae Collection.
The Saltwater Hobbyist use a larvae collecting device that works pretty well.
It comes with a small L.E.D. light to attract them to the entrance to the trap.
It is kept in place on the side of your tank will magnets.

I will look around and see if I can find a picture.
I will be picking one up to use in the future.
If anyone is interested in one, send me a P.M. for information.

[KenCotigirl]

I provide this because the larvae looks lethargic and remains on the tank bottom laying horizontal. Yesterday it stayed near the bottom but was floating in the head down position. It has been like this for at least 12 hours. I do not have much hope it will make it till morning. On the positive side my first try the larvae lasted 6 hours while this attempt is 84 hours and counting.

[Mustafa]

Thanks for the entertaining story. Looks like you're making some progress. So, how's the larva doing? You're right...the larva should not be lying on its side...unless there is some kind of light source entering its tank from the side, in which case the larvae of some species of shrimp tend to orient their tails towards that light source...even sideways. Do you have a bubbler in your setup set to bubble maybe maybe 1-3 bubbles per second (i.e. just a gentle current). The algae suck up all the oxygen when it's dark, which may negatively affect your current larva and future larvae.

[KenCotigirl]

The larvae passed on. I did not have a bubbler because I thought it would create too much current. I replaced 1/3 of the algae water twice a day with new algae water. The next try I will a bubbler 1-3 bubbles per second as suggested. This should be quite soon as the eggs on one female turned from solid to mostly clear with a much smaller yolk sac. Once the eyes appear on the larvae they are released within a day or two. Can't wait to get the larvae collecting device the Newjohn talked about. In the interim I will continue to use the penlight and check periodically. I may also try what I did the first time by accident, disturb the larvae carrying female. When disturbed she immediately releeased the larvae.

[Mustafa]

When disturbed she immediately released the larvae.

Hmmm..interesting. That should make collecting the larvae a lot easier. Just move the shrimp quickly to a small container...bug her until she gets annoyed and releases the larvae...remover her, and dump the container with the larvae into your rearing tank with the algae. Anyway, keep the updates coming. If the larvae keep dying, and you can exclude water parameters as the probable cause, then you'll have to try different food. I understand the larvae are not anywhere nearly as large as the H. rubra larvae, but if they are larger than Amano shrimp larvae, then they may require more than just algae...they may require zooplankton.

[KenCotigirl]

Forgive my ignorance but when you say zooplanton you mean rotifers and copepods? I could probably grow these in the algae I am now growing. This way I could have both food sources available at the same time.

[zapisto]

Forgive my ignorance but when you say zooplanton you mean rotifers and copepods? I could probably grow these in the algae I am now growing. This way I could have both food sources available at the same time.

copepods is probably too large but i would definifively try the rotifers.
but rotifer do eat the algae.....

[Mustafa]

Yes, rotifers and copepods (especially the smaller species and their nauplii) are worth a try. Newly hatched Moina may work, too (although they won't survive in saltwater for very long). If you have access to saltwater species of rotifers and copepods, you may want to give it a try. There are also dead suspensions of zooplankton sold in store for the marine hobby (to feed corals). For my freshwater larvae I always have a container of water sitting in the bakyard. It is chock full of moina, copepods and other zooplankton. May not be a bad idea to set something like that up if you have the space...that's a constant source of zooplankton.

Forgive my ignorance but when you say zooplanton you mean rotifers and copepods? I could probably grow these in the algae I am now growing. This way I could have both food sources available at the same time.

[KenCotigirl]

Just received a larvae trap from Chad V. of Minnesota. He makes these traps for Clown fish breeders. Going to install it this evening. Will update.

Ken P

[KenCotigirl]

Caught a M. lohena larvae this morning with the new larvae trap. At first I was a little disappointed as I only caught one larvae. However I noticed a female with advanced larvae still attached to her swimmerettes. I hope tonight she releases the rest. I placed the larvae in a container of Nanochloropsis sp. This time there is aeration.

Another interesting tidbit. This being the first time I successfully used the trap I realized that the aeration was insufficient. I need to increase the amount of air bubbles to push the larvae into the final chamber of the trap. The larvae remained in the second chamber of this 3 chamber device. But as luck would have it this turned out to be a good thing. I found in the third chamber what looks like small jelly fish. One as large as 5mm. Easily large enough to eat the M. lohena larvae. I will try to get a picture of it but being translucent it may not come out. Where did this come from and how can they live in brackish water, sg of 1.013?

[KenCotigirl]

Here is a picture of the jellyfish.

[KenCotigirl]

The larvae trap worked well with the increase in air bubbles. I caught several more larvae overnight.

[KenCotigirl]

This is my third try at keeping M. lohena larvae. Please do not worry I will not be giving daily updates. Just milestone updates. My first attempt lasted 6 hours and the other about 3 days. As of this update I have two groups of larvae that are 3 and 4 days old residing in the same tank. I have to thank Mustafa for stating that I should add air bubbles to the larvae tank. I believe this kept the tank fresh. Sorry for the poor pictures but the larvae are active and do not stay still for their picure.