[en] There is very little published information on the genetic and cytogenetic responses of fish to radiation. Since a large proportion of the low-level waste arising from the nuclear power industry is discharged to aquatic environments, this constitutes a significant deficiency in our knowledge. While it is not expected that fish populations are seriously at risk, confirmatory evidence would be useful and would also provide a basis for generalizations from the much greater body of information available for mammalian systems. A primary cell culture has been obtained from pooled embryonic tissue of the small tropical fish Ameca splendens. This material has two advantages from the point of view of cytogenetic studies: the diploid chromosome complement is 26, and the chromosomes are all fairly large and most have a well defined centromere. The spectrum of aberrations found in these cells after irradiation with ⁶⁰Co γ rays is similar to that found in irradiated mammalian cells in culture, and an acute dose-response curve has been obtained. (author)