Lecture 11 Flashcards
What causes an increase of jelly fish
- Fishing down the chain and removing predators
- Possible differences in eutrophication
What are large number of jelly fish a problem
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
Why is there a serious welfare issue with C.capillata
Due to the irritant whip-lash like injuries inflicted by nematocysts of broken tentacles passing over the surface of the fish
What does C.capillata act as a vector for
Tenacibaculum maritimum
What is seen histologically with jelly fish
- 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
What is the most damaging bacteria on water quality
- Blue-green alage - Cyanobacteria
How do fish suffer from algae
- Suffer directly from toxins or indirectly through damage to the gill epithelia, resulting in acute necorsis, swelling, pyknosis and congestion
What is gas bubble disease
- 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
Explain the process of gass bubble disease
- 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
What suffers the most from gas bubble disease
- 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
Heart fat cause
- 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
When are salmon susceptible to hepatic lipidosis
- 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
What are some signs of hepatic lipidosis
- 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
What is steatitis or pansteatitis
Inflammation of the visceral adipose tissue that is normally abundant around the pyloric caeca in salmonids
What is the histology of stratitis
- 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
What can steatitis be seen is sequal to
- Pancreatitis
- But also an idiopathic disease where vit E deficiency and/or rancid fat in the diet are possible causes
What is soybean-induced enteritis
- A number of enteritides occur but attemlts to reduce fishmeal in piscivorous diets - imporve sustainability - have few causes
Pathology of soybean-induced enteritis
- 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
What can ascorbic acid (Vit C) deficiency result in
- 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
What influences the dietary requirements for vitamin E
- Level of polyunsaturated fatty acids and other oxidants in the diet and fish tissues as well as the level of selenium
- White muscle degeneration
*
Pathological changes with the lack of vitamin E
- Lordosis
- Exophthalmia
- Splenomegaly
- Mottled liver
- Pale kidney
- Poor growth
- Ascites
- Microscopic anaemia
- Haematocrit and increased haemolysis
What is seen with a lack of Vit B5
Dermatitis and exudate-covered gill almellae with extensive hyperplasia
What is a lack of B1 associated with
- M74 in the eyed eggs of wilf samon and sea-trout int he Baltic area
What is a lack of B12 associated with
- Petechiae in carp
- Dwarfism in channel catfish
- Most commonly corneal opacity
What does Vit K deficiency result in
- Haemorrhage similar to some reportable disease - fish can also get warfarin poisoning via feed
What can cause catatact in farmed fish
- Numerous nutritional imbalances
- ZInc deficiency
- With A
- Amino acids
Explain cataracts
- Bilateral and result if denatured proteins in the lens or the result from infection
What is osmotic cataract a result of and what are some examples of it
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
What does Ulverative dermal necrosis cause
Areas of sunburn
Signs of Ulverative dermal necrosis
- 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
What are many developmental disease due to
- Genetic factors
- Nutritional imbalance
- Hypoxia
- Poor husbandry
- Contact with parasites such as Myxobolus cerebralis
When can neoplaisa arise
- Following exposure to certain cehemicals, heavy metals, ionizing radiation, chronic inflammation, UV radiation, certain viruses and pollution
