Swim bladder hypoinflation is associated with gut dysfunction and increased mortality in larval zebrafish (Danio rerio)

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University of New Brunswick


The swim bladder is a vital gas-filled organ in most bony fishes that allows them to maintain neutral buoyancy. Despite its significance, the consequences of inadequate initial inflation of this organ remain poorly understood. Previous research has suggested a connection between hypoinflation and mortality, but the underlying mechanisms remain unclear. Contrary to the theory that physostomes can inflate their swim bladders at any point after 4 dpf, I found significant increases in mortality associated with non-inflation, suggesting inflation must occur within a critical developmental period. Additionally, analysis of exogenous feeding in hypoinflated larvae challenges the contention that feeding is limited in this phenotype. I do however observe significant gut barrier degradation, gross morphological differences, and compromised lysosome activity in hypoinflated larvae. These discoveries offer crucial insight into the effects of hypoinflation on larval fish.