The main defences against fish diseases are, quality control of the habitat they live in, this includes filtration, oxygenation and a well balanced diet which then lowers stress levels.
This does not mean that certain fish will not get any diseases, but will reduce the risk substantially. By feeding fish with nutritious food may be ok for some types of fish, but others need to be balanced.
Certain types of ornamental fish are in the cyprinidae family, such as goldfish and koi, these types have a total lack of stomach but a very long gut, and can only take in about 1% of their body weight at any one time, whereas they need to eat about 20% depending on their age and size.
Tthis won’t stop them eating, but can cause disease though lack of nutrition and food rotting in their gut.
These types of fish need to be fed in small doses throughout the day so they can get their full amount of nutrition and stay healthy.
When running a healthy pond, with little or no disease, it is always good practise when introducing new fish to your pond to have some sort of quarantine set up, this makes sure that the fish you are adding to your pond have not got any disease that might affect the fish you already have, although not all diseases transmit to other fish, or in fact humans.
When using any type of medication to cure a disease, make sure you know the volume of water in the pond you are treating; low dosage will not cure the fish and could be a long drawn out affair, high dosage could end up killing and not curing them.
You will need to monitor the fish over the period of treatment, if stress levels rise then a partial water change should be carried out immediately.
The best cure of all is to keep a healthy and balanced pond at all times, as prevention is always better than cure.
Below are common diseases that fish can be vulnerable too.
Carp or Fish Pox.
Spring Viraemia of Carp.
Fin, tail or body rot.
Bacteraemia (mild) or Septicaemia (acute).
Body or Ulcer disease.
Cotton wool or Fungus disease.
Gill fluke infection.
Skin fluke infection.
Anchor worm infection.