Opae-ula has been available in Hawaii for several years and some hobbyists have been growing them for longer than us.  We're sharing what we know with everyone and learning from the old-timers.

           Sam is the highly respected Director of Science of The Nature Conservancy of Hawaii and for a number of years,  he has been breeding opae-ula in his office.   He is considered a world authority on trilobites,  a class of extinct marine arthropods. He's got an award winning website on the subject!  To find it, go to Google and use the search term:  "trilobites" and his is the top listing!

           On August 11, 2004,  he responded to my email and gave me a lead on how to contact John Maciolek.  He also included:

          For me, reproduction is the given when the `opae`ula are given enough space and hiding crevices, and other conditions are more or less "normal" for them (which is a truly impressive broad range of salinities, light conditions, and temperatures). 

          Samuel M. 'Ohukani'ohi'a Gon III, Ph.D.

          Director of Science, The Nature Conservancy of Hawai`i

           That really got my attention and I asked Sam for more information which follows.  ~~~David

         August 11, 2004 (same day): My most successful tanks have cobbles of either limestone or lava in them running from 1" to 3" in general diameter, and typically quite irregular, allowing for many hiding opportunities. My 15-gallon tank at work gets very bright indirect light all day, but never direct sunlight. Right now I seem to have a eutrophy problem, but I believe this will pass if I remove enough of the excess algae (which has bound up the excess nutrients into tissue). If you read Holthuis' original description, you will see that the actual term for the ecosystem is anchialine pool, not pond. I also have seen reproduction in half gallon and even one quart glass bowls in my office at the Nature Conservancy. ~Sam

          I replied requesting the significance regarding anchialine pond (or pool) terminology, gave him my understanding of the total habitat, and this is Sam's reply:

      August 16, 2004: Holthuis' paper makes it clear that anchialine pools are the external expression of a primarily hypogeal (underground) habitat, so your discussion of the true nature of anchialine pools is right on the money. I liken the pools to light-rich windows on the habitat, at which the opae`ula have optimal food, but they live much of the time in the lightless voids underground.

If you look in the dictionary, the difference between pool and pond are not great. Since Holthuis is the originator of the term, and since he used the term "anchialine pool" and not "anchialine pond" in his paper, it is simply proper citation protocol to refer to them by their original description.

I concur with the lower salinity argument.  When the salinity is too high I see less or curtailed reproduction. OR it could be that high salinity is just fine for adults, but the proper salinity for reproduction is lower.   Aloha, ~Sam

         A week later, I reported to Sam that I had made contact with John Maciolek and summarized the latest reports of reproduction. Sam provided the additional information:

August 23, 2004: All my larvae hover in the brightest corner of my tank at work. They are phototaxic and so assemble in large numbers there during the right times of year. Right now there are only about a dozen or so of the larvae in the bright corner of the tank. Sometimes there are 50 or more at a time. There are juveniles of all sizes as well, of course, a good size distribution that runs from just over a mm to large adult size.  ~Sam

          Something wasn't right!   Initially I didn't know much about Sam Gon's background,  only that he began reproduction trials when his son had to do a science project.  Obviously Sam had a broader more extensive knowledge base and finally got this from him!

August 25, 2004:   Actually I got started on this in 1986 when with Maciolek, Chai, Brock and others, we undertook a statewide overview of anchialine pools for the County of Hawaii. I've been in the field with those guys to some of the most famous anchialine pool sites in the state.

I've had my 15 gallon opae`ula tank with shrimp from Ewa pools (now destroyed) for well over a decade. I started with perhaps 40 adults and now I estimate there must be 500+ shrimp in there. The tank easily generates 200 larvae a year.

Having my son do an `opae`ula project was our idea, not his science teacher's. We were just walking around the house looking for things that might work well for a project, and stopped at the 5-gallon tank I have at home. If it hasn't been explained to you before, the set-up I use in my 15-gallon tank is simple: fill the tank roughly halfway with brackish water, ca 1 part seawater to 8 parts fresh.

On the side of the tank farthest from a light source, set up a pile of cobbles, ranging from half-fist to whole fist size, so that at the far end the cobbles come all the way to the top of the tank, and at the lit end, there are no cobbles at all. This creates a "ramp" of cobbles from one end of the tank to the other and a large cobble-free water column on the lit end. Thus half the tank's area is a dark maze of intercobble spaces, and half of the tank is well-lit water column in which larvae can hover freely. By the time all cobbles are in the tank, the water is raised to near the top of the tank as well. I hope the description is clear enough! ~Sam