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Diseases of a Non-infectious Nature
Disease Types Associated with Non-living Agents
1) nutritional diseases2) neoplastic diseases3) toxic substances4) miscellaneous origin
Nutritional Diseases
proper nutrition is essential to the health of all animals
nutritional diseases in fish are common and associated with either deficiencies or excesses
estimating the role of malnutrition in disease outbreaks involving opportunistic pathogens is essential
not really a problem among wild fish populations because they select a balanced diet
What you Can Do to Avoid Malnutrition
estimate proper ration requirement insure that moisture content is taken
into consideration when feeding are dietary supplements required? nutrient requirements proper feeding practices
Nutritional Requirements
protein and amino acids fatty acids protein:energy ratio vitamins minerals possibly fiber
Nutritional Diseases of Fish
most are chronic in nature usually develop slowly over an extended
period of time early disease symptoms may be subtle and
difficult to interpret Why?
1) often only moderate nutrient deficiencies or excesses are involved
2) signs of the disease can often be masked by secondary pathogens
Nutritional Disease Diagnosis
requires observation of external and internal signs
quantitative clinical chemistry on blood, tissues, fluids of infected fish
histopathalogical examination also may be useful to have your feed
analyzed to rule out deficiencies evaluate feed ration, frequency and quality of
feed management
Pathological Syndromesprotein/amino acids
reduced or abnormal amino acid intake in fish/shrimp results in reduced biosynthesis of many vital substances:
enzymes, hormones, certain pigments, and cofactors
certain amino acids are necessary for oxidation and utilization of fats/carbo's
amino acids also required for formation of purines, pyrimidines
diagnosis of malnutrition associated with protein or amino acid deficiencies is difficult due to being nonspecific
Protein/Amino Acid Deficiency
one sign is poor FCR, FCE for fish, this may be shown as anemia or low
blood erythrocyte count problem is that protein and amino acid deficiency
symptoms are similar to disease caused by other etiological agents
most common sign: reduction of growth for fish, deficiency of the EAA tryptophan will lead
to scoliosis and lordosis
Amino Acid Deficiency
other signs of tryptophan deficiency include cloudiness (cataracts) of the eye lens
this condition also occurs from deficiency of sulfur containing AA's
excesses of leucine or isoleucine increases valine requirement (antagonism)
Dietary Fats and Lipids
pathological conditions associated with:1) high fat intake or dietary fat2) deficiency in essential fatty acids3) or rancidification (peroxidation)
high fat intake = fat deposition in liver and obesity (yes, it's a disease)
check liver for fat droplets in water coldwater species and high saturated fat don't mix
(reduced digestibility, flexibility) deficiency of linolenic acid = de-pigmentation, fin
erosion, fainting
Fatty Acids unsaturated fats are subject to rancidification this is a process where peroxides and other toxic
compounds are produced peroxidation causes a syndrome similar to muscular
dystrophy (usually associated with alpha tocopherol Vit E)
incomplete metabolism of fat causes production of a pigment that is stored in the liver, affecting its proper function
no specific treatment for peroxidation
Carbohydrates excess soluble COH results in hyperglycemia, build-
up of liver glycogen and enlargening of the liver
the practical effect of this is not known
lethargy, darkening of color, poor appetite
increased glycogen storage in liver results in increased susceptibility to disease from bacteria, fungi, parasites
liver malfunctions
Mineral Deficiencies
hard to evaluate due to difficulty of removing minerals from diet and water
most famous study showed that fish can develop goiter (thyroid condition associated with iodine deficiency)
zinc implicated in eye cataracts low iron = anemia phosphorus deficiency = lordosis, skeletal
deformities, skull size
Treatments for Nutritional Diseases
protein/amino acid deficiency: confirm feed nutrient levels, rations, storage
lipids/fatty acids: analyze feed FA levels, insure quality at time of manufacture; reduce dietary lipid
carbohydrates: check liver glycogen content, blood glucose; reduce dietary level of digestible carbo's
vitamin deficiency: gross signs, blood chemistry, histopath; check storage, form of vitamin (e.g., ascorbic acid)
mineral deficiency: histopath on thyroid (iodine), lenses (zinc), blood (iron), etc.; confirm feed nutrient levels, form of mineral (digestibility)
Neoplastic (Tumor-like) Diseases in Fish
cell regeneration, growth, replacement occurs at a specific rate for specific tissues
if cell growth and proliferation occurs at an uncontrolled rate, you have a tumor
neoplasia = appearance of tumor mass hyperplasia = uncontrolled proliferation two types of tumors: benign and malignant benign tumors cause fewer negative effects than
malignant ones
Malignant Tumors cause formation of altered cells, altered
characteristics are passed on to other generations spread into blood, lymph or other organs is known as
metastasis tumors are also classified by tissue of origin, thus
"basal cell carcinoma" or "lymphoma" oncology or tumor study of fish is relatively recent
Causes of Neoplasia
as with other animals cause is obscure no single etiology can be found cellular changes result of multiple causes interacting factors: age, heredity, immunological
factors, presence of carcinogens, oncogenic viruses fish age and susceptibility may not be true since fish
continue to grow heredity: thyroid carcinoma in trout
Causes of Neoplasia heredity: susceptibility to aflatoxin,
some species more so than others presence of carcinogens: industrialized
areas = gonadal, liver tumors chlorination = neuroblastomas age effect has been shown in terms of
aquatic pollutants (even for embryos)
Malignant Tumors of Fish neoplasms have been found in nearly all organs and
cell types of fishes incidence, however, is quite low with typically little
effect on entire population major malignant tumor in fish is known as "hepatoma"
or liver cell carcinoma first reported in rainbow trout in 1933 result of feeding cottonseed meal that had spoiled in
the field, producing the fungus Aspergillus flavus the toxins from fungal spores were identified as the
primary etiological agent
Liver Cell Carcinoma: aflatoxicosis
there are no outward signs of aflatoxicosis or hepatoma during the early stages of tumor growth
enlargement of the liver may then take place and the fish becomes emaciated
as disease progresses, liver nodules grow and contact other organs
confirmatory diagnosis is via histopathology/oncology of the tumor
Hepatoma Therapy and Control
there is no therapy must eliminate aflatoxin from the ration in subsequent
generations usually eliminated from feeds by addition of
proprionic acid or ammonia treatment of the feedstuff prognosis: morbidity may reach 70% in culture
facilities linear relationship between cottonseed meal intake
and incidence of hepatoma
Idiopathic Epidermal Hyperplasia
Idiopathic Epidermal Hyperplasia (striped bass epithelium)
Stomatopapilloma in European Eel
X-cell Lesions in Gill Cavity of a blue whiting
Fibrosarcoma on a Goldfish
Mass in the throat of a porkfish caused by a thyroid tumor
Osteomas on the rib and vertebral column of an Atlantic croaker
Benign Tumors of Fishes have been identified for many fish species throughout
the world most cases are concerned with individual fish and not
the entire population benign tumors are usually by oncogenic viruses or
bacteria and may be more numerous than other types
good example in fish is the bacterium Mycobacterium fortuitum which stimulates production of tumor-like masses in the kidney, liver or spleen
other agents include copepod parasite which produce fibromas where they attach
