Red Volcanic Shrimp (Halocaridina rubra)

[Mothi]

How many Red Volcanic Shrimp (Halocaridina rubra) can I put in a 5.5g? How big a tank would 500 Red Volcanic Shrimp (Halocaridina rubra) need? hehe

Currently I have 12 in a tank that is <1g and am thinking of just going for a larger tank. I just love these little guys.

[Cajunspice]

These are the Hawaiian Red Shrimp which requires saltwater i believe... the data is in the "shrimp varieties" section provided by Mustafa...

as far as how big of a tank... looking at its size... u can use the thumb rule for other small shrimps for this one too, but i'm not sure what it is...

topics about the Hawaiian Red Shrimp has been posted multiple times before on this forum if you would just search it

[goniagnostus]

I estimate 500 - 800 in my 15 g tank, see details here:
[dead link]
Aloha,
Sam

I find lower salinities (2-4 ppt) and steady temperatures of ca 70F conducive for breeding. I recently received a group of about 10 mature shrimp from an anchialine cave from Wai`anae, O`ahu, put them in a 2 gal "brain jar" with some coral rubble and there are about 100 of them now, after a very productive summer...

[chlorophyll]

Hey! Welcome to the board, Dr. Sam.
I really liked Fuku-Bonsai's report on you and your opae.
I tried to set up a tank like yours but haven't had any reporduction. The opae grew quite large (over a full cm), but also developed whitish insides. I figured there was a water chemistry problem caused by some of the rocks I put in...

I'll have to go back and rework that tank soon. Will gradually lower the salinity too (currently 10 ppt). Most here who have had theirs breed seem to keep them at 20-25 ppt though.

[goniagnostus]

In Hawai'i, anchialine pools with greater than 10 ppt are considered high salinity pools, while the low salinity pools (the only ones in which I have seen zoea larvae under natural conditions) typicaly run 2-4 ppt. I generally begin with a 1:8 dilution of ocean water, taking the 35 ppt ocean-level salinity down to roughly 3-4 ppt. I use either coral rubble from above the high wave zone (so it is NOT live rock) or volcanic rocks, the more irregular shaped the better. I tend to ignore other aspects beside salinity (which I can get away with since Honolulu's tap water is artesian and typically not strongly treated). I keep a combination of steady temperature and high indirect light conditions (no direct sun!) to generate a good supply of algae. I do not feed or do so only very rarely. I am surprised people are getting reproduction under high salinity conditions. Several colleagues here in Hawai'i reported success with reproduction as they stepped down salinity during the summer months.
Best of luck!
Sam

[Mustafa]

Hi Sam,

Welcome to the forum! I hope you stay around for a while. It's hard to find people who have some tangible experience with the Opae ula, so anything you can contribute is highly appreciated.

As for breeding these shrimp, it seems that they are highly adaptable with regards to salinity. I have larvae and juveniles (and ovigerous females) right now happily living and breeding at 20-21 ppt salinity (this is what I just measured). My salinity usually fluctuates between 14 and 23 ppt depending on evaporation. Lately I had been a little lax on topping off their tank so the salinity has been at the higher end for almost two months. During this time I saw two batches of larvae and some juveniles.

I just took a picture of a juvenile (only a few days old and about 3-4mm) that happened to be sitting right on the front glass of the tank "begging" to be photographed as I was reading this topic.

Here it is:



Sorry for the bad picture, but that's all I could muster given the conditions. The "baby" shrimp is actually redder in real live. The camera did not quite capture it.

I have had reproduction occuring at 8-12 ppt before also, which underscores this species' adaptability. It's interesting that you note that most of their natural habitats have salinities under 10 ppt. That begs the question how high the salinity in the deeper parts of the pools is as low salinity water usually sits on top of the high salinity water. Also, did anyone try to somehow measure the salinity in the subterranean habitats that connect these pools together and also connect them with the ocean?

It also seems likely that the larvae could take full ocean salinity, which would make it easier for them to colonize new habitats on "new islands" (geologically young) that do not have Opae ula populations yet. It seems more likely than the adults walking over to these islands on the ocean floor. That would also explain why Antecaridina lauensis (another red anchialine pool shrimp for those who wonder) can be found at such disjoint locations all over the world, including Hawaii, Solomon Islands, Japan, Madagascar, the Red Sea and even in the Atlantic (Bermuda). I understand that these might just be remnants of ancient populations (as the leading theory suggests), but still they need some way to move to new islands once these prop out of the ocean.

As to temperature, the temperature in their tank right now is 78 degrees, but I have had reproduction occur at 80-82 degrees also. This again underscores their ability to adjust to various conditions.

Finally, have you ever tried breeding these shrimp in hard, high PH freshwater? If you can breed them at 2-4 ppt you might actually be able to do the same at 0 ppt salinity. I am going to try it out at some point once my Opae population is large enough but I was just wondering if it had been tried before.

For such an interesting shrimp there seems to be very little research on this species.

Again, welcome to the forum and I am looking forward to your contributions.

Mustafa

[goniagnostus]

I certainly agree about the wide range of conditions for 'opae'ula. They are extremely tolerant, which explains their success as mini torture chamber pets, and a shame that most people don't get to see their fuller potential when offered a better habitat. I have never taken them gradually down to entirely fresh, though it would not be too difficult a task. Maciolek, Brock and others have informally tried this, and they do not take well to long-term freshwater conditions, though they can tolerate it for a while (days).

I have had a population in a 50 gal tank that has never reproduced, though the individuals within have reached maximal size and are nearly 7 years old! max size is about 1.5 cm and molt interperiod greatly slows, some of the oldtimers have algae growing on their exoskeletons and they swim so leisurely that it seems like slow-mo.

Thanks for the welcome message Mustafa!

Sam

[chlorophyll]

Hey, I have 3 individuals in a lab at UH who I've kept in freshwater since last December. They seem to have taken to it well, however even after a year I guess it's hard to say how their long term health is affected since these shrimp have such long life spans. They're in with duckweed (which they like to hang around on) and are accompanied by a colony of amphipods and cypris who hitchhiked on the duckweed. They've grown substantially and have good color. I started that mini experiment with 5 individuals but two died... I think that had to do with some ignorant overfeeding on my part though.

Never tried to induce breeding in freshwater (which I had planned to do).... because I haven't even had them breed in brackish yet. Do you have any idea why those in your 50 gallon tank never reproduced?