Nephrocalcinosis in Fish – Gross pathology

Figure 1. Gross appearance of nephrocalcinosis. The kidney is swollen and grey with an irregular surface and white mineral deposits in the ureters.

Nephrocalcinosis (or urolithiasis) in fish is a chronic inflammatory condition of unknown aetiology in which calcium and other minerals precipitate as hydroxyapatite within the distal renal tubules and collecting ducts. The disease usually records low mortality and although food conversion efficiency is probably impaired, the major concern about the condition centres round a reduction in carcase quality at slaughter. In severe cases, the muscle dorsal to the kidney may also be affected. There are some predisposing factors for this condition like high levels of carbon...

Caligus Rogercresseyi – Gross Pathology

Atlantic salmon with adult females (C. rogercresseyi). Note the lesions on the skin surface. Note also the paired trailing egg sacs.

Caligus rogercresseyi is a predominant parasitic problem in the salmonid industry in Chile. It mainly affects Atlantic salmon and Rainbow trout. Coho salmon is not considered susceptible due to a well-developed inflammatory response. The life cycle of C. rogercresseyi is composed of eight stages of development, two nauplius stages I and II, an infested copepodite stage, four chalimus stages and an adult stage (young adult and mature adult). The amount of time it takes for a louse to develop depends greatly on the temperature. Under...