Husbandry of the annual killifish Austrofundulus limnaeus with special emphasis on the collection and rearing of embryos

Annual killifish development is unique compared to other teleosts and is ch aracterized by the dispersion and subsequent reaggregation of pre-embryonic blastomeres and the occurrence of embryonic diapause. Austrofundulus limna eus is an excellent species to use for studies of development and embryonic diapause in annual killifish. A. limnaeus has a high fecundity, reproduces readily in a laboratory environment, and has a relatively long laboratory life span compared to many other species of annual killifish. Methods are p resented for rearing A. limnaeus in the laboratory with an emphasis on coll ecting and incubating large numbers of embryos for biochemical and physiolo gical studies. Females produce an average of 29 eggs during a two to four h our spawning. Egg quality (% fertilization and survival) and egg production (eggs female(-1)) are affected by the number of days between spawning even ts. Percent fertilization of eggs and survival of embryos decreases as the interval between spawning increases from two to eight days. The number of f ertile embryos produced per female remains relatively constant as a functio n of spawning interval. Fertilization rates may be maintained at high level s by replacing aged males (1.5 years old) with younger males. An embryo med ium was formulated to mimic the natural waters inhabited by A. limnaeus. Th e developmental rate and survival of embryos in the embryo medium was essen tially equivalent when compared to Yamamoto's fish saline solution.