Deposition of aluminium in gills leads to chloride cell necrosis or at lower levels, to inhibition of the enzymes carbonic anhydrase and/or gill NA+, K+ – ATPase (NKA), required for seawater tolerance. Such changes impair osmoregulatory capacity and cause physiological stress due to disruption of gas and ion transport, altered blood chemistry and hormonal imbalance.
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Bone deformities occur regularly in fish farms around the world. The operculum is one of the earliest craniofacial bones to form embryologically and is subject to a range of developmental and acquired abnormalities. Opercular shortening is one of the most prevalent diseases in larval and juvenile salmonids (and other species), sometimes affecting up to 80% of fish in a population. In those species that rely on the operculum to help move water over the gills, loss of efficiency in this part of the pumping mechanism...
