Rapid cooling via dry ice preserves the genetic and morphological integrity of fish embryos

Larval fishes provide a valuable metric for assessing and monitoring species, populations, and ecosystem trends and condition. However, taxonomic resolution for this life stage is inherently problematic because of their individual sizes, limited morphological characteristics and high tissue degradation rates. There is little research on methods that rapidly preserve larval tissues for later morphological and molecular identification. The goal of this study was to test methods of rapidly killing fish embryos that maintain both morphological and molecular integrity. Rapid cooling with dry ice successfully maintained morphological and molecular integrity and may offer a simple and cost-effective approach for larval fish identification.