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Updated: Jul 4, 2025

Raising the Mexican Tetra Astyanax mexicanus for Analysis of Post-larval Phenotypes and Whole-mount Immunohistochemistry
Published on: December 28, 2018
The dwarf neon rainbowfish Melanotaenia praecox, a small spiny-rayed fish with potential as a new Acanthomorpha model
Kazuhide Miyamoto1, Gembu Abe2, Koji Tamura1
1Department of Ecological Developmental Adaptability Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
Background:
Fish fins with highly variable color patterns and morphologies have many functions. In Actinopterygii, the free parts of fins are supported by "soft rays" and "spiny rays." Spiny rays have various functions and are extremely modified in some species, but they are lacking in popular model fish such as zebrafish and medaka. Additionally, some model fish with spiny rays are difficult to maintain in ordinary laboratory systems.
Results:
Characteristics of the small, spiny-rayed rainbowfish Melanotaenia praecox render it useful as an experimental model species. Neither fish age nor body size correlate well with fin development during postembryonic development in this species. A four-stage developmental classification is proposed that is based on fin ray development.
Conclusions:
Melanotaenia praecox is an ideal species to rear in laboratories for developmental studies. Our classification allows for postembryonic staging of this species independent of individual age and body size. Development of each fin ray may be synchronized with dorsal fin development. We discuss the differences in mechanisms regulating soft, spiny, and procurrent ray development.

