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Although it is widely accepted that the cellular and molecular mechanisms of vertebrate cardiac development are evolutionarily conserved, this is on the basis of data from only a few model organisms suited to laboratory studies. Here, we investigate gene expression during cardiac development in the extremophile, non-model fish species, <i>Oreochromis (Alcolapia) alcalica</i>. We first characterise the early development of <i>O. alcalica</i> and observe extensive vascularisation across the yolk prior to hatching. We further investigate heart development by identifying and cloning <i>O. alcalica</i> orthologues of conserved cardiac transcription factors <i>gata4</i>, <i>tbx5</i>, and <i>mef2c</i> for analysis by in situ hybridisation. Expression of these three key cardiac developmental regulators also reveals other aspects of <i>O. alcalica</i> development, as these genes are expressed in developing blood, limb, eyes, and muscle, as well as the heart. Our data support the notion that <i>O. alcalica</i> is a direct-developing vertebrate that shares the highly conserved molecular regulation of the vertebrate body plan. However, the expression of <i>gata4</i> in <i>O. alcalica</i> reveals interesting differences in the development of the circulatory system distinct from that of the well-studied zebrafish. Understanding the development of <i>O. alcalica</i> embryos is an important step towards providing a model for future research into the adaptation to extreme conditions; this is particularly relevant given that anthropogenic-driven climate change will likely result in more freshwater organisms being exposed to less favourable conditions.