CHAPTER 3 - EMBRYONIC AND LARVAL CULTURE
(Source: C. Walker)
For optimal growth during the first few days, keep the embryos in system water at least 3 cm deep (25-50 embryos per 100 ml in a 250 ml beaker, for example). Embryos can also be raised 25 per 35 mm petri dish if the water is changed daily, although this method does not provide for optimal growth. The best temperature for growth and for accurate staging is 28.5°C. Placing the beakers in a constant temperature water bath and covering them with watch glasses provides steady conditions. The embryos normally hatch after about 3 days of development but do not need to be fed until 4 days after fertilization. At that time, feed the larvae live paramecia or other microorganisms which can be prepared as an infusion. Most pet shops sell infusion materials for feeding baby fish. Paramecia raised in a mung bean culture reduce the chances of infection. At 9 days, the food can be switched to both paramecia and baby brine shrimp and finally adult-type fish food (see Food, page ). As the larvae get larger, they can be moved to bigger containers. For maximal growth keep the number of fish per container low, feed them often (twice daily) and replace about 1/3 of the water in each container daily.
General method for raising babies:
1. Keep 15-25 embryos in 100 ml system water in a 250 ml beaker. The best temperature for growth and staging is 28.5°C, but embryos survive temperatures between 24°C and 33°C. Placing beakers in a constant temperature water bath and covering them with a watch glass provides steady conditions for accurate staging. Embryos hatch in between 2 and 3 days.
2. At 4 days after fertilization, feed embryos live paramecia (or other microorganisms, available at most pet shops, which can be prepared as an infusion. Feed large quantities of paramecia starting at 6 days because the yolk is mostly depleted by then.
3. At 9 days, move fry into 1-2 liter baby rearing containers and feed both paramecia and brine shrimp. Clean containers care-fully twice daily, replacing with clean system water. Gradually increase the proportion of brine shrimp and phase out the paramecia.
4. At 21 days, move fish into tanks, still feeding them baby brine shrimp. Feed adult foods as soon as the babies are big enough to eat it.
The Zebrafish Book