Evidence rule
1. SUPPORTED — experimentally demonstrated, peer-reviewed, or strong government/agency evidence.
2. HABITAT/TOLERANCE — conditions occupied or survived, not necessarily breeding optima.
3. HUSBANDRY CLAIM — breeder/specialist practice that worked for the source but is not a controlled optimum.
Halocaridina rubra — regular ʻŌpae ʻula
Thomas Iwai Jr. (Hawaiʻi Division of Aquatic Resources) reported a captive reproductive population at 23–25 °C, 18–20 ppt salinity, and 12 h light : 12 h dark. About 23% of females spawned under those conditions. Brooding was about 30 days, with 5–21 eggs per spawn.
A separate long-running research colony maintained multiple genetic lineages at 15 psu, 24 °C, porous volcanic substrate, microbial/microalgal grazing surfaces, and controlled light. Those colonies reproduced consistently but sporadically for many years.
Taken together, the strongest direct captive evidence supports 15–20 ppt and roughly 23–25 °C for reproductive colonies. The 18–20 ppt range is the most directly documented spawning setup; 15 ppt is strongly supported by long-term colony maintenance and larval survival experiments.
Metabetaeus lohena — Alpha Opae
Alpha Opae are not a Halocaridina morph. They are alpheid shrimp with a different reproductive strategy.
The no-yolk observation originated as T. Iwai unpublished work but is reported in a peer-reviewed population-genetics paper, so Aquapedia keeps the evidence chain explicit.
There is no complete, reproducible captive breeding protocol established in the sources reviewed.
Breeding-risk note
Do not mix adult survival, natural occupied habitat, successful adult spawning, and successful larval metamorphosis. They are different evidence categories. This distinction is especially important for Alpha Opae, where adults can berry under captive conditions while the larval cycle still fails.
Machine-readable claim-by-claim evidence, including unverified hobby reports, is stored in data/shrimp/opae-ula-breeding-parameter-evidence.v1.ndjson.
Public research references
Listed research leads are not automatically supporting evidence for every individual claim.