TIDBITS (NIBBLES) ON RAISING ZEBRAFISH BABIES
By K.C. Cheng, E. Kauffman, and E. Gestl, Department of Pathology, Penn State, M.S. Hershey Medical Center, Hershey, PA 17033
Use of fine nylon mesh to remove undesirable protozoa from zebrafish embryo cultures.
We have found that paramecia fed to zebrafish babies are, on occasion, accompanied by an overgrowth of small ciliated protozoa (5-50 microns) that are inevitably present in paramecium cultures. This overgrowth can produce a rapid loss of zebrafish. We have recently saved several cultures by pouring the entire culture with the zebrafish larvae through 5 micron nylon netting (we used Nitex brand, available through Argent Laboratories, 1-800-426-6258); this allows most of the smaller protozoa to squeeze through. Filtration is slow enough to keep the fish in water at all times. Most of the volume of the tank can be decanted to minimize the time required to wash the zebrafish culture, and the collected fish can then be rinsed with an excess of clear water. We began with three cultures, each of about 25 nine-day old leopard zebrafish in 24 x 14 x 13 cm mouse cages half-filled with water in which small, ciliated protozoan overgrowth was present. Twelve embryos were lost in an hour. These cultures were washed, replaced in their original tanks after washing with dechlorinated tap water (during filtration), filled half full with fresh prewarmed dechlorinated water, and fed with powdered food. No embryos were lost over the next 24 hours.
Small brine shrimp for feeding baby zebrafish.
After feeding of young (4-12 day old) embryos with paramecia or powdered food, brine shrimp feeding is used to accelerate growth. During the early days of feeding (after about day 9), we have noted that the brine shrimp are often too large for many of the zebrafish to eat. There are two solutions to this problem. First, Grade 0 Platinum label Argentemia from Argent Chemical Laboratories yields smaller brine shrimp than other sources. This is a relatively expensive solution. An alternative is to take advantage of the large variation in size of brine shrimp (from 250-700 micron length) by differential filtration. To separate the smaller from larger brine shrimp for those first feedings, we use 220 micron nylon netting. The brine shrimp that pass through the 220 micron mesh are collected using either 100 or 120 micron mesh and fed to the babies. The larger ones are fed to the larger babies. For the first brine shrimp feedings, we simultaneously continue feeding Microfeast L-10 and spirulina powder until all the fish are eating brine shrimp.
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