Chapter 1: Methods in Fish Biology: the Modern Toolbox
Prosanta Chakrabarty, Stephen R. Midway, and Caleb T. Hasler
Why do we need a biology book with methods specific to fishes? Phylogenetically speaking, all vertebrates are fishes, so the real question is: do we need any other kind of biological methods book besides this one?
Some techniques are unique to fishes (sensu stricto): everything from the convention of always taking measurements and images from the left side of the body to more specific husbandry and developmental studies. This book will hopefully highlight for the reader everything general and specific you will need to study any and all types of fishes.
Biologists studying fishes (e.g., ichthyologists, fish biologists) have been ahead of other types of organismal experts in a number of areas. Fish taxonomy, for instance, is greatly enhanced by “Eschmeyer’s Catalog of Fishes,” an exhaustive, free, online, and up-to-date record of synonyms and valid taxonomic names of all fishes (Fricke et al. 2021). Eschmeyer’s catalog includes the roughly 300–400 fish species that are described each year, and many others that are renamed, sunk, or taxonomically resurrected. No other vertebrate group, despite all being substantially less taxonomically rich, can boast an equivalent resource. But it isn’t just in taxonomy that fish studies are ahead. The first vertebrate genome sequenced after Homo sapiens was that of Takifugu rubripes, the Japanese Pufferfish (or Fugu), which has a genome so small that there are larger prokaryote genomes (Brenner et al. 1993). At the same time, the largest genome also belongs to a fish: this Mount Everest of genomes belongs to the lungfishes (Dufresne and Jeffery 2011; Meyer et al. 2021). Therefore, the smallest vertebrate genome belongs to an advanced ray-finned fish, while the largest belong to a sarcopterygian (or lobe-finned fish; you and all tetrapods belong to this lineage, too). The mysteries within our DNA, and that of all vertebrates, lie within these extremes.