Copper toxicity in fish

Liver from Atlantic salmon fingerling showing positive copper reaction in hepatocyte cytoplasm. Rhodamine stain. Note the intracytoplasmic granules (bright red or rust-red) that correspond to lysosomes with sequestered excess copper (arrow).

Copper is a significant trace element necessary for the normal growth and metabolism of living organisms. However, if there is overexposure, it can be toxic. Levels of dissolved copper are often increased from anthropogenic origins such as mine washings and direct applications of algicides, molluscicides or antifouling agents. The most toxic form of copper is the cupric ion (Cu2+). Fish and crustacea are 10 to 100 times more sensitive to the toxicity of copper than mammals. For salmonids, the upper recommended limit is < 0.03...

Tenacibaculosis in Fish – Gross Pathology

Figure 1. Rainbow trout displaying tail and peduncle lesions.

Tenacibaculosis is primarily a skin infection causing ulcerative dermatitis in a range of commercially important species worldwide. Three species belonging to the genus Tenacibaculum have been associated with the disease: T. dicentrarchi, T. finnmarkense, and T. maritimum.   These bacteria are all Gram-negative and filamentous.  In marine fish, the most common isolate is T. maritimum. There is variation in the external pathological signs of the disease, depending on the species and age of the fish involved. Different names have been used for this usually ulcerative dermatitis; they include salt water columnaris...

Short operculum – Gross Pathology

Figure 1. Severe opercular erosion in farmed rainbow trout.

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...

Cardiomyopathy syndrome in Atlantic salmon (CMS) – Histopathology

CMS in ventricle of Atlantic salmon showing severe myocarditis of spongy layer. Note that the compact layer (on the left) is largely unaffected.

Cardiomyopathy syndrome (CMS) is a severe cardiac disease affecting Atlantic salmon characterized by prolonged periods of usually low-level mortalities. The disease was first recognized in farmed Atlantic salmon in Norway in 1985 and subsequently in farmed salmon in the Faroe Islands, Scotland and Ireland. CMS is a transmissible disease that has been causally linked to the Piscine Myocarditis Virus (PMCV), closely allied to the Totiviridae. CMS usually causes mortality in adult or maturing fish after 12 to 18 months in seawater, resulting in substantial economic...

SPINAL FRACTURE DUE TO ELECTRIC SHOCK

Atlantic salmon, presmolt, FW, exposed to electric shock. Note the spinal fracture associated haemorrhage. The cause of the electric shock was an energized cable that fell into the tank.

Bone is a highly anisotropic, viscoelastic material that has the ability to continually adapt to changes in its physiological or mechanical environment. The capacity of bone to resist mechanical forces and fractures depends not only on the quantity of bone tissue but also on its quality. Bone is a composite material, made from a collagenous matrix and from minerals. The collagenous matrix provides toughness (fracture resistance) and the minerals increase the bone’s stiffness (bending resistance). By itself, the mineral phase is brittle and fractures easily....

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