In aquariums, ponds and fisheries it's important to be able to recognise normal and abnormal behaviour. If you can know and recognise your fish's normal behaviour, this should help you in indicating abnormal behaviour. Healthy fish display normal behaviour. If a fish's normal behaviour changes, the fish keeper needs to discover what the cause of the problem is. If abnormal behaviour does occur the water quality should be checked first, or if there is an over stocked fishery or aquarium there might be problems with stress from competing with each other for food and territory. Change in weather and temperature can also have many affects on fish. below is some examples of fish behaviour. Resting
Fish do not always swim around, a fish that is not stressed will sometimes find somewhere to rest up and hide away from the fishery or aquarium. This also happens in the wild.
If a fish is hiding to regularly or all the time, this can be an indication that it could be stressed or unwell.
When the temperature drops suddenly or the winter months are present, fish can become less active and rest more in the undergrowth or tree roots where the temperature can be warmer.
A good way to indicate if your fish are healthy is to monitor the way they swim.
If your fish are stressed they tend to swim differently eg: swimming lethargically at the surface and gasping for air. This can be a sign of low dissolved oxygen.
Swimming around on their side or floating rather than swimming
They also swim into shallow areas and almost breach themselves
When the fish lays at the bottom of the lake bed or aquarium and does not swim in a normal manor this can mean they are unwell.
A healthy fish will always be able to maintain stability when swimming and feeding.
If your fish are healthy and food is presented to them they should feed vigorously.
When feeding your fish the best method is to feed them on the surface, this is so you can monitor the way they feed and spot any irregularities.
Fish can be hard to find so feeding is a good way find and monitor their progress.
If reduced feeding is taking place you should investigate the cause immediately
Colder weather conditions can have an affect on feeding
Flight behaviour is when a fish is actively swimming around or taking evasive actions.
Fish will actively swim around when happy and feeding.
When a fish is stressed and in flight or fighting with other fish they release a stress hormone called cortisol.
High levels of cortisol can cause negative effects. The main effects would be a lowered immune response which would open doors to parasites and disease. the stressed fish will also have a reduce growth rate and this could cause deformities when growing on.
If the fishes body doesnt return to normal and relax they could become chronically stressed
However small increases can have positive effects
A small amount of cortisol released can give fish a burst of energy and a burst of immunity. this all helps with the fishes ability to be able to grow and be healthy.
Here is some useful information that I used to gain my qualifications :