Crowded jewel fish show changes in dendritic spine density and spine morphology

This study demonstrates that neuronal development can be adversely affected by short-term crowding. Compared with uncrowded siblings (15 fish/73-litre), juvenile jewel fish (15 fish/3.6-litre) crowded for 60 days exhibited 50-58% fewer dendritic spines and spines with narrower heads on pyriform interneurons in deep tectal strata. These findings indicate that crowded environments can produce aberrant neuronal development similar to that seen in socially deprived jewel fish.