Anyone breeding Palaemonetes pugio?

[Pugio]

I live in the DC (USA) area and in Oct '06 collected a few Palaemonetes pugio from a creek that flows into the Patuxent River - an estuary of the Chesapeake Bay. Over that time I have been able to successfully raise the adult shrimp in *essentially* fresh water (1 tablespoon-full of sea salt is added for every 5 gal water change in my 10 gal tank- to inc. hardness). The site of collection of these shrimp is so far up the Patuxent River that there is zero tidal surges and no salinity (I checked it) - but high hardness / suspended particles.

I have been able to raise larvae to ~2 weeks of age and they had doubled in size over that time being fed brine shrimp <72hr old. (This brood died when I was away for Xmas and neither my girlfriend nor buddy could duplicate my demanding regimen - my fault). Regardless I estimate they had reached at least the 5th molt (maybe 7?) based on published literature I could find.

I think I have finally developed a technique that can breed this shrimp in captivity, with tight control of oxygen, waste byproducts and temperature.

I have fallen in love with this shrimp species. They are amazing to watch and I have decided to finally get rid of my livebearer tank after 7 years. No comparison - vertebrates seem so 2006.

I have the following questions:
1. Has anyone raised P. pugio? If so, how did you raise the larvae through the prolonged larval stage and how long did it take? What am I in for here?
2. What about salinity? Anyone have ideas about the possibility of "historically brackish-water" shrimp having clades or sub-species that can tolerate freshwater (ie, how do brackish-water shrimp species living in freshwater replenish their stocks year after year?) It's my theory that my P. pugio must have evolved to tolerate 100% freshwater - otherwise juveniles would have to migrate 50+ miles down- and then up-river to replenish freshwater stocks each spring. And the Patuxent is a slow mover. Do Amano shrimp migrate this far (>100 miles round trip?). -- The Chesapeake was only formed about 10,000 years ago (the very VERY end of last Ice Age)- so if it was initially populated by brackish/marine Palaemonetes (from more southern waters) isn't it possible for the founder population to evolve into an intermediate, freshwater-tolerant species as they moved into fresh-water rivers? Am I thinking too much?

Here's a pic of one of my females with eggs. Eyes of pre-hatch larvae are visible in eggs. Note the small, yet numerous (100's) eggs - which I understand to be typical of shrimp that have extended larval development (ie, marine/brackish).


I have plenty more pics. Looking forward to any good responses. I have read everything there is to find on P. pugio from the internet (and I don't trust half of it ). Thanks for any help/info! Pressing on...next brood due in next couple weeks.

~Pugio

[Neonshrimp]

Hi and welcome Pugio,

I think I have finally developed a technique that can breed this shrimp in captivity, with tight control of oxygen, waste byproducts and temperature.

Sounds like you are ahead of the game on this subject and could give us some details as you add to this thread.

No comparison - vertebrates seem so 2006.

Am I thinking too much?

Never. Thoughts, questions and answers are what drive drive this forum and expands the hobby!

Again welcome and I hope the best for your next brood!

[badflash]

Welcome aboard!

I suggest you raise the salinity up to about 1/2 seawater for the larva. Most of these brackish shrimp likely end up in the sea as the larva can't fight the current.

You might also want to add some live marine algae to the mix. This may add food, but will also scavenge waste from the water. Saltwater rotifers are also easy to culture and would probably be good food for them.

[badflash]

I did a little review and found this:

Field and
laboratory studies indicate that P.
pugio adults tolerate salinities from-0
to 55 ppt but are most common in
salinities of 2 ppt to 36 ppt (Wood
1967; Swingle 1971; Bowler and
Seidenberg 1971; Christmas and Langley
1973; Kirby and Knowlton 1976; Morgan
1980). The 96 h LDso values for adults
are 0.5 and 44 ppt (Kirby and Knowlton
1976).
Attempts to assess salinity
tolerances of larvae on a broad scale
have yielded mixed results. McKenney
and Neff (1979) were able to rear
nearly 50% of the P. pugio larvae
exposed to a salinity of 3 ppt,
whereas, Broad and Hubschman (1962)
reported poor survival of larvae at
salinities less than 10 ppt. When
larvae were exposed to a wide range of
arbitrarily selected salinities, the
low and high salinities required to
kill 50% of the larvae during a 96-hr
exposure (LD50) were 16 ppt and 46 ppt,
respectively (Kirby and Knowlton 1976).
Optimum salinity for complete larval
development is 20 to 25 ppt (Floyd
1977; McKenney and Neff 1979; Knowlton
and Kirby 1984). Possible reasons for
the conflicting findings are
differences in populations in different
geographic locations, and differences
in laboratory procedures.

This is taken from:
Biological Report 82 (11.35)
March 1985
Larayette, La. 70506
TR EL-82-4
Species Profiles: Life Histories and
Environmental Requirements of Coastal Fishes
and Invertebrates (Gulf of Mexico)
GRASS SHRIMP

[Pugio]

Badflash - Thanks for the welcome and info. I've seen that info as well but have hesitated so far in increasing the salinity in the hopes (or false belief) that I may have collected a low-salinity tolerant shrimp. My hope was to be able to breed these shrimp in freshwater...

I think I should probably split the broods between freshwater and ~20ppt salinity from here on out - to hedge my bets and see what happens.

Are rotifers better than brine shrimp? I had thought of that but didn't really see anyone using them for brackish shrimp - outside of large-scale shrimp farmers. I'll have to consider that.

[badflash]

Rotifers are about 1/3 the size of brine shrimp and won't grow. Depending on the size of the larva, it might be a good food source as is the Tetraselmis. You would need to keep separate cultures of the TET and rotifers. You also need to be VERY carefull not to contaminate the tet with rotifers, or you'll end up with no more tet.

[Pugio]

So finally the *two* surviving P. pugio larvae have metamorphosed into post-larvae. I may have lost track of when their brood hatched but I think it was 34 days ago according to my logs. Most of that brood died due to carelessness and cluelessness. I should note that the larvae were raised in "hardened" freshwater (1 tbsp seasalt/5 gallons).

Here's a picture of one of the post-larvae (left) next to a 5 day old larvae from my most recent brood - with artemia around:


Now I need a grow-out tank. I was thinking of setting-up a 2.5gal with a sponge filter...

[Neonshrimp]

Wow, thanks for the picture of the young shrimp side by side, you can really see the difference. What are the white things surrounding them, they look like brine shrimp.

Best wishes on your new brood!

[Pugio]

Yep - those are brine shrimp ~48hrs old. The larvae were raised on 100% baby brines. I found this article: http://www.biolbull.org/cgi/reprint/112/2/144, that showed highest survival rates with brine shrimp for P. pugio & vulgaris - although I was probably the last in the shrimp hobby to figure this out...



...so highest % post-larvae survived with Artemia nauplii. Probably rotifers would be similar but I dunno. I should count the # molts in next brood but 6-8 sounds about right. If only discarded exoskeletons made nice jewelry...

I don't see any way that larval shrimp can survive after the 1st molt without food - it seems crucial that they be fed and that timing is of the essence Although I've seen sellers who suggest that "mature," aged aquariums may be able to support larvae - but I just don't think a run-of-the-mill filtered aquarium can cultivate a high enough density of planktonic "stuff" to support freshwater shrimp larvae...seems like a sales gimmick to me.

[badflash]

I would try rotifers because they won't foul the water. You can just feed the tank green water & the rotifers will keep going. Rooootifers are super easy to grow, you just need to keep sterile when working with the green water or you will have the rotifers eat it all. This means growing the green water in a different room. Rotifer eggs can be carried by the air and the adults can easily be transferred on your hands, nets, etc.

[Mustafa]

Congrats! I did read reports of P. pugio larvae making it to adulthood in low salinity, but the the percentage of larvae making it is lower at lower salinities. All else equal, more larvae should survive in higher salinity water. You might want to try about half strength sea water and see how it goes. You can adjust from there depending on larval survival results.

I should note that the larvae were raised in "hardened" freshwater (1 tbsp seasalt/5 gallons)

[Pugio]

So all of your suggestions are well taken. My success rate must be <2% with hardened freshwater...as I only have two juveniles now. 100% loss with last brood. If it is possible to selectively breed a freshwater tolerant P. pugio it'd take a lot of effort. Anyone selectively breed shrimp other than for color?

So now I got a new brood from my favorite, best-colored female. I thought I'd show the modified fish breeding trap I use to collect the larvae born last night.

Curiously, the larvae always begin hatching between 10-11pm. Its like clockwork. Done hatching by 1:00am. Maybe timed with the photoperiod?

[Neonshrimp]

I thought I'd show the modified fish breeding trap I use to collect the larvae born last night.

Did you seal the water vents with silicone?

Curiously, the larvae always begin hatching between 10-11pm. Its like clockwork. Done hatching by 1:00am. Maybe timed with the photoperiod?

That is interesting and convenient for you to know when delivery time is

Thanks for sharing.

[Pugio]

Yes - I covered the vents with a plastic mesh used to hold charcoal material and sealed it on with silicone. About 1-2 days before hatching the larvae's eyes in the eggs become very bright (with flashlight and magnifying glass) and then ~1 day before hatching the eggs swell up a bit. When I see bright eyes and swollen eggs - that's when I put the female in the trap and wait for 10pm to roll-around. I have NO idea if this works for other species. The first picture in my post is an example...

[Neonshrimp]

That is a great tip to help others gauge the expectant dates. Thanks Pugio