The holy grail of opae’ula hobbyists is the Nishijma Bottle, the gallon jar that Dr. Wayne Nishijima1 created as a habitat for opae’ula. He began the experiment in 1988 and started an international craze that is still growing. By all accounts, his tiny tank is still thriving.
The hoopla is that the original colony of opae, or shrimp, has survived since 1988, making it 27 years old as of this writing. That in itself is an amazing discovery, but toss in a few other facts and you begin to understand why Nishijima’s experiment has captured people’s imagination:
- The colony has never been fed.
- The tank has no mechanical filtration.
- The water is from the original collection site.
- The water has never been changed.
- The glass has never been cleaned.
The only thing that’s kept me from attempting a similar experiment is the lack of a suitable one-gallon glass bottle. I finally found one at the local Sam’s Club, containing Vlasic pickles. I transferred the pickles into smaller containers for storage in the fridge and rinsed the bottle. No detergents. Just a thorough rinse, by hand, with tap water. I also filled it with water and left it standing overnight to get rid of the remaining traces.
Here’s a rundown of features:
Stock: Stocked the colony with seven opae from the 18-gallon tank.
Water: Transferred cycled water from the 18-gallon to the 1-gallon. I also included a bit of algae from the 18-gallon.
UGF: The stock round UGF was a perfect fit, so the chances of gravel getting into the open area under the filter were slim. This negated the need for a layer of small coral rocks to separate the gravel from the UGF. I’m using a charcoal filter unit at the end of the exhaust tube because the tube was too short. I’ll probably get a longer tube and eliminate the filter unit for the sake of aesthetics, space, and easy maintenance.
Cover: In place of a clear glass dish, I’m using a small ceramic dish. The dish is important because it reduces evaporation. I’m placing it right side up with the bottom forming a convex surface that drips evaporation or bubble splash back into the tank instead of out the sides. I’m retaining the metal cover that came with the jar for possible use when moving the setup.
Air filter Air pump: Small 10-gallon pump with a check valve in the line to control the outflow.
Hypogeal stratum: Larger coral rocks to maximize visibility of opae activity. I also make an effort to stand them on end, Stonehenge fashion, with the smaller end in the gravel to facilitate viewing and to maximize the exposed gravel surface for better flow.
Except for the layer of small coral rocks, I pretty much followed the design that I used with my oblong 2-gallon tank.
My goal in departing from the classic Nishijima design is to create an environment that will encourage breeding. The theory is that the hypogeal coral layer and the current created by the UGF more closely simulate the opae’ula’s natural habitat.
I have it on my desktop where I can observe developments closely and frequently. Hopefully, I’ll begin to see some berried females once the bottle settles into the green algae phase.
1 Background source: “Evolution of Opae-Ula Ecosystems” on the Fukubonsai website.