Husbandry of the Annual Killifish Austrofundulus limnaeus with Special Emphasis on the Collection and Rearing of Embryos

Abstract

Annual killifish development is unique compared to other teleosts and is characterized by the dispersion and subsequent reaggregation of pre-embryonic blastomeres and the occurrence of embryonic diapause. Austrofundulus limnaeus 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 presented for rearing A. limnaeus in the laboratory with an emphasis on collecting and incubating large numbers of embryos for biochemical and physiological studies. Females produce an average of 29 eggs during a two to four hour spawning. Egg quality (% fertilization and survival) and egg production (eggs female-1) are affected by the number of days between spawning events. Percent fertilization of eggs and survival of embryos decreases as the interval between spawning increases from two to eight days. The number of fertile embryos produced per female remains relatively constant as a function of spawning interval. Fertilization rates may be maintained at high levels by replacing aged males (1.5 years old) with younger males. An embryo medium was formulated to mimic the natural waters inhabited by A. limnaeus. The developmental rate and survival of embryos in the embryo medium was essentially equivalent when compared to Yamamoto's fish saline solution.