Page 170 - WSAVA2017
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An Urban Experience
protozoa). But enteric infections with bacteria such as Pseudomonas can also present in a similar fashion.
The common term of ‘dropsy’ is used when there is
also protrusion of the scales to create a ‘pine cone’ appearance due to subcutaneous edema. This is obvious in fish with larger scales, but is difficult to appreciate in species such as the angelfish with fine scales. Dropsy
is often accompanied by ‘pop-eye’ (exophthalmia). These are commonly a result of primary or secondary bacterial infections causing inflammation and vascular damage, especially to the rich vascular beds in the kidney and choroid rete behind the eye. The insult to the kidney interferes with fluid balance, causing the ‘dropsy’ appearance and inflammation behind the eye causes the ‘pop-eye’ appearance. There is one breed of goldfish where exophthalmia is selected and these are known as telescope moors.
Fish in advanced disease can present with buoyancy disorders. They may either become negatively buoyant and sink to the tank floor, or become positively buoyant, floating to the surface. This is a very common condition in goldfish breeds and in my experience, it is more common in rotund breeds such as the ryukin, pearl scale and orandas. These fish tend to also have twin tails. There is suggestion that fish should not be overfed and that they should be given adequate fiber in their diet. Systemic bacterial infections are also common causes
of buoyancy disorders. Less common causes include coccidial and fungal infections of the swim bladder.
Fish that are wasting present with concave abdomen. The differential diagnoses for poor body condition in fishes include, but are not confined to the following: chronic malnutrition, or infections by bacteria (e.g. mycobacteriosis), protozoal organisms (e.g. Hexamita, Spironucleus, Cryptobia, Sporozoa, Ichthyobodo) and metazoa (e.g. Gyrodactylus, Dactylogyrus and a number of cestode species). Fish with enteropathy will have long fecal strings, that may contain bubbles and float, or they may be empty fecal strings (in most freshwater fishes, normal fecal casts should resemble black string). If they are overfed, their fecal strings take on the same color
of the fish food fed to them. Those with enteritis will display congested vents. This can be overlooked when assessing health of pond fish. Thus it is very important to capture some fish to examine their vents.
Causes for sudden death are difficult to diagnose because fish tissues autolyse rapidly. Based on epidemiological principles, sudden death is likely due to environmental causes. Collating a good history and water quality analyses are important.
Inappetance is a non-specific sign of illness. It can
also occur when water temperature deviates from their tolerance range. The most common is during winter when owners are unaware that they need heating for their Siamese fighting fish, or their heater has stopped working. You will see remains of uneaten food in the tank or filter.
So we have discussed the clinical signs displayed by fish during ill-health. But some other things we should also consider include their environment. Fish that are sick tend to produce more mucus and you may notice a fishy smell coming from the tank and perhaps there may be excess stable foam accumulating at the water surface.

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