Peppermint shrimp moulting prior to larvae release

[Hordeum vulgare]

Hello, I want to breed some peppermint shrimp but am having the following problem;

The shrimp all moult prior to releasing the larvae, and when the moults are retained in a seperate tank the larvae never release, despite showing indications of near complete development (eyes can be seen on larvae within eggs). This suggests that it is a larval development issue and is not a direct result of adult behaviour. Furthermore the adults moult at about the right time for egg release (10-12 days), further suggesting it is directly related to larval development and not to adults.

The shrimp are fed frozen prawn and sometimes squid, live in a large tank and I have tried various things to make the larvae release including
-removing/changing macroalgae (In case of toxin/chemical release inhibiting larval development (I know this is a long shot))
-changing light conditions
-changing vessel, have had the shrimp in 80 litre tank connected to a larger system, also in 5 Litre tanks.
-changing temperature; was running whole sytem around 28.5 C, now dropped to 27.5 C

I have made my own salt water and the latest change is to take out my carbon filter and start dosing iodide, as macroalgae and normal cycling slowly depletes this element. I am yet to see the result of this effect. But as I make my own salt water, the water will also have low Br-, F- among others.

I am currently reading up on crustacean moulting/development in hope I find clues there

Anyone had this problem, and if so, how did you fix it?

regards

Sam

 

[ginpang]

I haven' t tried to raise fry ... But neither of my lysmatas moult before releasing the fry . ( amboineensis, wurdemanni)

sg at 1.024
Temp at 76
Nh4 =0
No2=0
No3 =0
Po4 = always
Ca=440
Iodide added once or twice a week.
And reef builder once a week.
And chitons reproducing like crazy in there ...
I leave bryopsis growing for all kinds of microorganisms to hide in and feed on. That way if ever larvea would make it . It could also hide and feed in it.

Good luck



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[Keoki18]

What is your flow in your hatching system? Have you ever tried force hatching the eggs when you remove the molt to a separate system (sucking them up with a turkey baster an blowing them out)? I have been raising cave shrimp (P. uveae) and noticed that I was having similar issues when there wasn't enough flow to rasp the eggs open. as soon as I installed a small power head my holding adults swam straight to the flow and started releasing.

 

[Hordeum vulgare]

Hello,

Both good answers on factors I havent considered. Thanks a lot :bounce3:

Ginpang;
Your water parameters look a lot better than mine, the system I am using is quite young (February 2016) and I have been having problems with ammonia spikes up to 1 mg / L when adding new batches of live rock, but the moults retaining eggs issue has occurred both during and inbetween ammonia spikes so I am putting that factor out of the equation for now

sg at 1.024 (32 ppt)
Temp at 82 (27.8 C)
Nh4 =0.25 - 1 ppm
No2=0
No3 =<5
Po4 = 0.25 ppm
Ca=unknown (my test kit is giving me over 1000 ppm, but I want to verify it with a different kit)

The iodine supplemetation has begun (added half seawater concentration last week (half of 0.055 mg / L as KI), will add the next half this week (i am assuming my iodine is low, but getting a test kit to verify this)

How much iodine are you adding?

Keoki18

The tanks have minimal flow through, and I have been turning the flow off at night to retain larvae in the tank

Judging by your finding this also looks like an area that I should rectify. From your observations it appears that mechanical rather than chemical means (larvae releasing enzyme to break through the egg chorion/shell/whatever it is). Perhaps the tear in the shell occurs at the point where it is attached to the pleopods, and hence the shell remains attached and is another reason for moulting when no obvious increase in size occurs.

Thanks you two, you've given me a lot to ponder.

Can anyone verify that part of the eggs remains on the moult attached to the pleopods?

 

[ginpang]

Peppermint shrimp moulting prior to larvae release

The tank that has the inverts in it is only a 45 gal. so I put one capful twice a week ( in that one) .Which is pretty much the recommended dose on the seachem bottle. I can' t take the credit for inventing anything.

I started using it because I had bought l. amboineensis on rebate because they had black spots That I knew were indicative of bad moults. And I had learned this trick years ago that a boost in iodine could make it all better. [emoji56]


I'll try and see if shell parts remain attached next time ... She usually has eggs at the same time my jawfish has . So probably another 3-5 weeks.

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[Keoki18]

Absolutely agree with ginpang on the iodine dosing. It is extremely helpful in producing normal molts for any crustaceans. Like any system, I would recommend stabilizing your water parameters a bit more if possible. Deffinetly reduce that NH4 to 0 and possibly lower you PO4. Calcium should rest between 375 and 450ish (it can be higher, but not necessary IME).

Good question about the post spawn attachment of spent egg cases. I am not 100% sure, but I do believe the entire larvae (egg included is released). I simply let the holding adults breed and incubate the brood in a 40 gallon display tank. When I start knowing advanced development with the eggs (usually 1 month or so) I move the adults to a spawning system (10 gallon tank with a 1" hole drilled near the top for over flow, a gravity fed hose line from the display to the 10 gallon, several PVC pipes). I collect spawn 2 ways..

1) I allow the shrimp to toss their larvae into the flow, that flow siphons them from the 10 gallon tank into a small critter keeper (effectively separating the adults from the fry). The critter keeper has been turned into a pseudo-kreisal that keep the fry tumbling. the water then flows from the critter keeper back into the DT sump. So the whole system look like a cascading stair case. I have the most success with this method.

2) I have made an fry collector that sits in the 10 gallon breeding tank. It collects the fry right from the water with out needing to be fed from the DT (10 gallon is completely stand alone). Issue with this is that water quality is a bit difficult to control, and the fry may die off if you don't catch them soon enough.

 

[Hordeum vulgare]

Well I have added the second dosing of iodide to make seawater strength iodine concentrations.

Went through the math on the seachem iodine product, and was surprised how high they were recommending to dose in relation to seawater

For instance

iodine concentration

Natural Sea water - 0.055 mg / L (around about depending on location)

Seachem recommendation - 0.06 - 0.08 mg / L

Seachem dosing actual - 0.2 mg I / L every second day (5 ml of 8 mg I / ml solution in 200 L tank)

I note that the recommend levels in the tank similar to seawater in the tank, but then on the other hand recommend a dosing level that is close to three times NSW, and to repeat this every second day

If it works it works i suppose, but it suggests that iodine turnover/loss aquariums are quite high

I am not game enough to dose at such high levels so will dose 1/3 rd of NSW concentrations per week (at least until I get the test kit)

I have also installed a submersible pump in the peppermint shrimp tank to get "the flow" going. Will keep you posted on how it turns out. Been dying to give my Kreisel a go since i built it several months ago

 

[Keoki18]

Sounds great. certainly keep us posted. Good luck!

 

[ginpang]

That's very interesting...Maybe iodine levels work for me because I forget 1/3 of the time[emoji23][emoji23][emoji23]


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[Hordeum vulgare]

Still waiting.....

Here is an image of the shrimp if it works on this site (has been requested on another site due to the complex nature of the Lysmata spp complex of the "peppermint shrimp group"



thumb_DSC_0635_1024.jpg

 

[Hordeum vulgare]

No didnt work....

 

[ginpang]

Peppermint shrimp moulting prior to larvae release

Ok she has eggs again ... Earlier than expected.... ( Time flies by !) first saw eggs on Saturday.
I'll pay more attention to the moult and egg release to see if I experience anything similar to what you're describing.

I know someone shed because there is debris floating into the anemone . It would make sense that she would shed around the time of having eggs but since she's in the Dt and not the only shrimp in there it makes it difficult to know who shed when.

When you say : shed Pryor to release. How many days or hours are you talking about?


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[Hordeum vulgare]

They appear to moult at about the right time for release (10 to 12 days, i stopped taking records as it was just effort for no results), but the release never happens. I can see the eyes of the larval shrimp so they appear near to, or right on, fully developed

To keep you updated on the situation, the shrimp should have released in the last couple of days judging by the brown eggs, but when i checked the shrimp again, they had green eggs. Couldnt even find the moults this time, but they are in a much larger tank, so this isnt saying much.

Anyway, I moved the shrimp out of larger system and into a standalone 75 litre tank inside. The temperature control is not as good, tank experiences 3 C (5-6 F) temp changes over a 24 h period, but is a thriving community of macro algaes, oysters and sponges, without the ammonia problem I have in the other system were the shrimp were held prior.

So will keep you posted on how that goes...

 

[Hordeum vulgare]

Success!

Well, not full blown, but close enough, have approximately 10 larvae.

This occurred in the stand alone tank (75 L). I woke up to see a shrimp exoskeleton without eggs attached and saw several shrimp larvae swimming around, then used black plastic to cover the tank sides and a flashlight to concentrate them at the surface. I assume the rest were destroyed by the filtration system.

After all the changes I made its difficult to determine what change or changes made the difference

Factors that may have resulted in the larvae being released prior to moulting (natural scenario) are
- Diet, shrimp switched from prawn to fish based diet; Perhaps a prawn based diet may directly influence the hormone balance of the peppermint shrimps, they may have similar hormone types as they are more closely related to each other than to fish (its a long shot). Also the tank environment may provide more copepods, amphipods and other marine life that are not present in the larger system
- Water quality; 1. this may come in the form of iodide dosing, 2. or from replacing around one third of the tanks water with NSW, but this was half way through the current incubation (approx five days ago), 3. increasing the tank alkalinity and hence decreasing the Ca levels, as my tanks had high Ca and low KH which i have now fixed (although I havent checked numbers) 4. Decreased ammonia concentration, as the 75 L tank they are in has <0.1 mg / L ammonia versus the 0.5 - 1 mg / L in the previous system.
- Temperature; the temperature has dropped where I live so I can now easily maintain the tank at 25 - 26 C versus the previous approx. 28 C in my previous attempts
- Water flow; the 75 L tank has a good circular flow motion, water in top sucked out bottom

Its only early days, and its a little early to count my chickens, but with a new enthusiasm i know plan to

Transfer the shrimp to the Kreisel system, use only NSW as replacement water, feed only fish and squid, and maintain lighting in the system to allow macroalgae growth. Theoretically the shrimp larvae should enter the Kreisel section straight after spawning. Hopefully with good maintenance goodwater quality can be maintained in the system, but time will tell. I assume that this method will mean that feeding inert diets is out of the question and only artemia and copepods, will be required

 

[ginpang]

Congrats! Keep us posted...

I currently see eyeballs through the eggs of two shrimps , I'll keep observing as well. I'll share if anything strange or relevant happens.


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[Keoki18]

Fantastic news! I'm glad you were able to collect some larvae.

 

[Hordeum vulgare]

Update....

Since my last post, I moved my remaining two peppermint shrimp to the delivery side of my Kreisel tank (water flows from this side directly into the Kreisel cylinder). I maintained the shrimp in NSW with 12:12 h light cycle (LEDs) at 27-28 C, with feedings of chopped fish and prawn, along with artemia.

Shortly after moving them I awoke to a Kreisel full of peppermint shrimp larvae, followed by a second batch about three days later. The shrimp are currently 10 or 7 days old, and appear to be going strong. Based on previous posts by Luis describing peppermint shrimp development, the most advanced larvae are at around Zoea 5 stage, but havent looked under the microscope. I got more larvae today from another spawn, so the saga continues. There has been no mass mortality to date, which I attribute to constant cleaning of the tank bottom and regular and large water changes (50% day)

Keep you updated

 

[Keoki18]

Looking good. What are you feeding your larvae? the can eat a considerable amount while they are phasing.

 

[ginpang]

Awesome !!! Pictures[emoji1376]


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[Hordeum vulgare]

Artemia, chopped fish, possibly copepods if I can get this show rolling. But yes I have noticed a lot of artemia are dissapearing, although I have had a hard time actually seeing a shrimp larvae eating one. I have seen them clinging to the chopped fish, so I assume their gnawing on that. Just attempting to get some DHA in them