skeleton with dislocations, focal haemorrhage and atrophy
are noted (Fig. 10.17). A reduction in collagen and irregular
hyalinisation of the remaining tissue results in a loose structure and dysplasia, including osteoporosis. Within the gill
lamellae marked cell degeneration of the cartilaginous rod
with large vacuoles accompanies deformation and distension
(Fig. 10.18). Fish may show a hypoplastic anaemia and a
decrease in haematopoietic tissue can be seen in the anterior
kidney. Macroscopically, a shortened operculum is a
common feature (Fig. 10.19). Gross appearance of the fish
and the examination of histological sections provide provisional information for a diagnosis. An analysis of the vitamin content of the feed should be carried out to support a
diagnosis.
Vitamin E is an essential nutrient for many species of fish
and deficiencies can occur where diets are partly oxidised
before use. Several factors influence the dietary requirement
for vitamin E, including the level of polyunsaturated fatty
acids and other oxidants in the diet and fish tissues, as well as
the level of selenium. A deficiency has an impact on several
tissues including observations of white muscle degeneration
(Fig. 10.20) and under experimental conditions, it is
associated with calcification of the pseudobranch
(Fig. 10.21).
Pathological changes include lordosis, exophthalmia,
splenomegaly, mottled liver, pale kidney, poor growth and
ascites, and can be correlated with marked microcytic
anaemia, reduced haematocrit and increased haemolysis.
Incomplete maturation of these cells is consistent with
increased fragility due the recognized role in cell membrane
integrity and growth. In addition, steatitis has also been
reported as well as small areas of degeneration with dilation
of the liver sinusoids often with ceroid deposition. Splenic
haemosiderosis is prevalent and occurs as a fine, stippled
appearance to the tissue in Perl’s stained sections (see
Fig. 4.22) and this correlates with the accelerated
Fig. 10.14 Soybean enteritis in farmed Atlantic salmon
Fig. 10.15 Farmed rainbow trout fingerlings with vertebral abnormalities resulting from vitamin C deficiency
10.3 Dietary Imbalance
159
are noted (Fig. 10.17). A reduction in collagen and irregular
hyalinisation of the remaining tissue results in a loose structure and dysplasia, including osteoporosis. Within the gill
lamellae marked cell degeneration of the cartilaginous rod
with large vacuoles accompanies deformation and distension
(Fig. 10.18). Fish may show a hypoplastic anaemia and a
decrease in haematopoietic tissue can be seen in the anterior
kidney. Macroscopically, a shortened operculum is a
common feature (Fig. 10.19). Gross appearance of the fish
and the examination of histological sections provide provisional information for a diagnosis. An analysis of the vitamin content of the feed should be carried out to support a
diagnosis.
Vitamin E is an essential nutrient for many species of fish
and deficiencies can occur where diets are partly oxidised
before use. Several factors influence the dietary requirement
for vitamin E, including the level of polyunsaturated fatty
acids and other oxidants in the diet and fish tissues, as well as
the level of selenium. A deficiency has an impact on several
tissues including observations of white muscle degeneration
(Fig. 10.20) and under experimental conditions, it is
associated with calcification of the pseudobranch
(Fig. 10.21).
Pathological changes include lordosis, exophthalmia,
splenomegaly, mottled liver, pale kidney, poor growth and
ascites, and can be correlated with marked microcytic
anaemia, reduced haematocrit and increased haemolysis.
Incomplete maturation of these cells is consistent with
increased fragility due the recognized role in cell membrane
integrity and growth. In addition, steatitis has also been
reported as well as small areas of degeneration with dilation
of the liver sinusoids often with ceroid deposition. Splenic
haemosiderosis is prevalent and occurs as a fine, stippled
appearance to the tissue in Perl’s stained sections (see
Fig. 4.22) and this correlates with the accelerated
Fig. 10.14 Soybean enteritis in farmed Atlantic salmon
Fig. 10.15 Farmed rainbow trout fingerlings with vertebral abnormalities resulting from vitamin C deficiency
10.3 Dietary Imbalance
159