Visualization of Unhatched Brine Shrimp Eggs in Zebrafish Intestines Using Synchrotron Radiation Phase-Contrast CT

Brine shrimp are an ideal bait for zebrafish with high protein content. In laboratory settings, brine shrimp eggs (BSEs) are commonly used to hatch for acquiring brine shrimp. However, not all BSEs are able to successfully hatch into brine shrimp. Actually, some unhatched BSEs (UBSEs) retain and are collected along with the brine shrimp as bait. The digestibility of UBSEs and their potential impact on the digestive system of zebrafish have not been demonstrated. In this study, high-resolution synchrotron radiation phase-contrast CT (PCCT) was used to show the internal structures of UBSEs. Morphological changes of UBSEs were investigated after digestion in zebrafish intestines. The visualization of shell rupturing, collapsing, and shattering of UBSEs reveals that zebrafish intestines exerted much extra useless effort to digest the UBSEs. The results indicate that UBSEs should be completely discarded from the bait of brine shrimp before feeding zebrafish.