Examine a fish

Examining a fish is the process of assessing its physical condition through the observing its motion fluidity, scale condition, fins, eyes, sliminess and body shape/condition.

It is an important skill because fish are typically housed in large groups and are therefore exposed to identical water conditions. For example if the concentration of nitrate ions is too high in the water only a few fish may show noticeable physical inhibitions (e.g. the loss of large patches of scales) but all fish will have their growth stunted to some degree. Hence routine examinations of fish is an important skill as it is the easiest and one of the most efficient methods of assessing the performance of your animals.

A fish can be examined though:

1. Examination: Which is more common used and involves the assessment of fish condition through sight.

2. Physical Assessment: Which is much more labour intensive (especially in large aquariums) and involves the removal of the fish onto a wet towel or shallow tub for a more thorough assessment. Typically this is only conducted after a individual has been isolated through examination.

Examining a fish
The majority of fish found in aquariums and aquaculture should be alert and mobile as its movement drives many vital processes such as respiration. Therefore observation is an important component of the physical examination process. The following are things to look out for:
 * 1) In a large system, fish should be alert and active with quick responses to stimuli such as splashing and not bumping into other fish or the tank walls. An easy way to test this is to throw some food into a corner and any fish lagging behind or swimming haphazardly should be removed for further inspection. This method can be done easily though both an overview of the system or a side-view if the tank walls are transparent.
 * 2) A smaller aquarium or isolation tank can allow for a closer examination of the fish, notable features include:
 * Fluidity of motion: no erratic movements as they often result from pain or irritation.
 * Appearance of scales: should have none missing in large patches, which would indicate the loss of mucus due to stress e.g. high nitrite or ammonia levels.
 * Healthy fins and eyes: Ragged fins are rare in aquariums that are well stocked and maintained and unusual in large aquaculture systems. A high percentage of fish with fin wounds suggest overstocking, poor water quality or issues with feed composition and/or timing.


 * Any other physical or behavioral abnormalities compared to the other fish.Examination a fish

Physical Assessment of a fish
Usually however, a more thorough physical assessment of an individual fish is required. This can be done through a physical assessment. As a fish can remain out of water safely for a few minutes, a physical assessment can be quickly conducted on features such as:
 * Sliminess: The mucus layer of a fish protects it from waterborne pathogens and limited or excess mucus production indicates stress from chemical imbalances in water, temperature or overstocking.
 * Struggle: A health fish should flail in a net in an attempt to escape while a sickly fish will not provide much resistance.
 * Body Shape and Consistency: In a healthy, well-fed fish you should not be able to feel any bones or irregularities in its streamlined body. Similarly all fish reared in the same conditions should have a consistent weight.

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