Lecture 11

Question 1

What causes an increase of jelly fish

Answer 1

• Fishing down the chain and removing predators
• Possible differences in eutrophication

Question 2

What are large number of jelly fish a problem

Answer 2

Hit the cage, some go in.

Can result in anoxia in the cages or obstruct respiratory causing respiratory distress

Traumatic enucleation of the eye and marks on side of fish

Question 3

Why is there a serious welfare issue with C.capillata

Answer 3

Due to the irritant whip-lash like injuries inflicted by nematocysts of broken tentacles passing over the surface of the fish

Question 4

What does C.capillata act as a vector for

Answer 4

Tenacibaculum maritimum

Question 5

What is seen histologically with jelly fish

Answer 5

• Sloughed lamella and necroses
• Oedema and inflammation of the filamenta as emphasised by the presence of granulocytes
• After 48h there is evidence of epithelial sloughing, haemorrhage and lysis of erythrocytes

Question 6

What is the most damaging bacteria on water quality

Answer 6

• Blue-green alage - Cyanobacteria

Question 7

How do fish suffer from algae

Answer 7

• Suffer directly from toxins or indirectly through damage to the gill epithelia, resulting in acute necorsis, swelling, pyknosis and congestion

Question 8

What is gas bubble disease

Answer 8

• Non-infectious physically induced process that is cuased by incompensated hyperbaric pressure of total dissolved gases within the fish vascular system
• Can occur as a natural phenomenon in lakes and rivers or artificially when supersaturated water is drawn into fish tanks without adequate aeration

Question 9

Explain the process of gass bubble disease

Answer 9

• When pressure compensation is inadequate, a sudden decompression in the external environment leads to blood dissolved gases to form emboli in several tissues asit abruptly comes out of solution when trying to balance with the decreased external pressure

Question 10

What suffers the most from gas bubble disease

Answer 10

• Highly vascularised tissues suffer most and severe exophthalmia due to the physical accumulation of gas bubbles in the choroid gland of the prosterior uvea
• Macroscopically bubbles may also be seen in the mucous membranes lining the oral cavity, the gills and fins
• Gas bubbles in the heart cavity cause the fish to die from asphyxiation
• Gill damage: oedema of the lamellae with degeneration of the covering respiratory epithelium occurs with tissue necrosis and ischaemia of the capillary beds

Question 12

Heart fat cause

Answer 12

• Scarcity of fish meal protein has resulted in their gradual replacement by plant components
• Prolonged storage of feed under unfavourable conditions may compromise the quality and inconsistency may occasionally occur

Question 13

When are salmon susceptible to hepatic lipidosis

Answer 13

• When fed polyunsaturated fatty acids combined with insufficient amounts of antioxidant protection, such as vitamin E
• Polyunsaturated fatty acids are prone to auto-oxidation on exposure to atmospheric oxygen

Question 14

What are some signs of hepatic lipidosis

Answer 14

• Anaemic with pale gills and ascites
• Internally: yellow-orange discolouration and slight enlargement of the liver with a friable fatty consistency
• Haematocrit is usually severly depressed
• Accumulation of excessive lipid in hepatocytes, macrophages and fat storing cells

Question 15

What is steatitis or pansteatitis

Answer 15

Inflammation of the visceral adipose tissue that is normally abundant around the pyloric caeca in salmonids

Question 16

What is the histology of stratitis

Answer 16

• Thickening of the adipose cell walls, infiltration, aggregation of ceroid containing macrophages and pigment deposit
• A granulomatous response centered on multinucleate giant cells and eosinophillic inclusions

Question 17

What can steatitis be seen is sequal to

Answer 17

• Pancreatitis
• But also an idiopathic disease where vit E deficiency and/or rancid fat in the diet are possible causes

Question 19

What is soybean-induced enteritis

Answer 19

• A number of enteritides occur but attemlts to reduce fishmeal in piscivorous diets - imporve sustainability - have few causes

Question 20

Pathology of soybean-induced enteritis

Answer 20

• Thickening of the lamina propria due to infiltration of macrophages, neutrophils, eosinophilic granular cells
• Absorption from the gut is reduced sue to loss of apical vacuoles in the epithelial cells

Question 21

What can ascorbic acid (Vit C) deficiency result in

Answer 21

• Imapired biosynthesis of collagen and chronic reduction of the supporting tissues giving rise to a typical kyphosis, lordosis or scoliosis
• Hypoplastic anaemia and a decrease in haematopoietic tissue
• Macroscopically a shortened operculum

Question 23

What influences the dietary requirements for vitamin E

Answer 23

• Level of polyunsaturated fatty acids and other oxidants in the diet and fish tissues as well as the level of selenium
• White muscle degeneration
  *

Question 24

Pathological changes with the lack of vitamin E

Answer 24

• Lordosis
• Exophthalmia
• Splenomegaly
• Mottled liver
• Pale kidney
• Poor growth
• Ascites
• Microscopic anaemia
• Haematocrit and increased haemolysis

Question 25

What is seen with a lack of Vit B5

Answer 25

Dermatitis and exudate-covered gill almellae with extensive hyperplasia

Question 26

What is a lack of B1 associated with

Answer 26

• M74 in the eyed eggs of wilf samon and sea-trout int he Baltic area

Question 27

What is a lack of B12 associated with

Answer 27

• Petechiae in carp
• Dwarfism in channel catfish
• Most commonly corneal opacity

Question 28

What does Vit K deficiency result in

Answer 28

• Haemorrhage similar to some reportable disease - fish can also get warfarin poisoning via feed

Question 29

What can cause catatact in farmed fish

Answer 29

• Numerous nutritional imbalances
  
  • ZInc deficiency
  • With A
  • Amino acids

Question 30

Explain cataracts

Answer 30

• Bilateral and result if denatured proteins in the lens or the result from infection

Question 31

What is osmotic cataract a result of and what are some examples of it

Answer 31

Fluctuating osmolality where the fish is unable to adjust to the environmental salinity

• Temperature fluctuations, gas saupersaturation and exposure to UV light
• Keratitis may result from physical, nutritional, chemical or thermal damage to the cornea or it may be casued by an infectious agent

Question 32

What does Ulverative dermal necrosis cause

Answer 32

Areas of sunburn

Question 33

Signs of Ulverative dermal necrosis

Answer 33

• Small superficial grey coloured head lesions above the eye, along the snout or adipose fin often with erosion on the cranium, to deeper ulcers involving large areas principally on top of the head
• Later stages, secondary infection with Saprolegnia parasitica is frequently associated eith the open wounds

Question 34

What are many developmental disease due to

Answer 34

• Genetic factors
• Nutritional imbalance
• Hypoxia
• Poor husbandry
• Contact with parasites such as Myxobolus cerebralis

Question 35

When can neoplaisa arise

Answer 35

• Following exposure to certain cehemicals, heavy metals, ionizing radiation, chronic inflammation, UV radiation, certain viruses and pollution