Zebrafish go through a total mid-life crisis in just a few weeks, switching from loving the light to being terrified of it.
March 20, 2026
Original Paper
Behavioral algorithms of ontogenetic switching in larval and juvenile zebrafish phototaxis
bioRxiv · 2025.06.13.659371
The Takeaway
This study identifies a rare behavioral inversion where the animal's fundamental navigational instinct completely reverses during development. Researchers mapped the exact shift in the neural algorithms that rewrite the fish's brain 'software' as it matures.
From the abstract
Animals undergo major behavioral adjustments during ontogeny, but how the underlying cognitive algorithms change during this process remains elusive. Here, we describe that zebrafish shift from light-seeking to dark-seeking, as they grow from larval to juvenile stage, within the first few weeks of their life. We apply a combination of complementary phototaxis assays in virtual reality and modeling to dissect the computational basis of this transition. We identify three parallel pathways, one ana