Fish are no more prone to illness than any other animal and, like all animals, have over time evolved an immune system specific to the basic ills that afflict them. Therefore the best means of keeping fish healthy is by keeping their environment in tiptop condition, a healthy pond invariably means healthy fish.
There are however a few simple basic rules to observe.
1) Before you fill or top up a pond ensure that the water supply is suitable for
fish; there is no guarantee that tap water is, The water companies are only
required to supply water fit for human consumption. Not fit for fish.
2) Unless you have a serious problem it is best not to change more than 50%
of the pond water at any one time.
3) Do not keep topping up a pond through evaporation without first removing
some water, from the bottom of the pond if possible, around 10% a week
during the warmer months and 10% a month during the winter.
4) Never treat fish or the pond with a chemical in case something may occur.
5) If you have to treat a particular fish always isolate it from the others.
A 113lt uPVC cold-water tank from a local Builders Merchant serves
as a good hospital or quarantine tank.
Fill with 50% pond water and then top up with a suitable tap water.
6) If you have to treat a complete pond turn off any UV units and
Particle Filters. Isolate Biological filters but maintain a minimum flow
of water pumping the samewater around a biological filter to keep it going,
or the Biomass will die.
Remove any plants that the treatment may affect; also plants and planting
medium will absorb the chemical making it difficult to measure the correct
7) Do not introduce any new fish into an established pond without first
keeping them in Quarantine for the period recommended by the supplier.
8) Do not treat a fish or pond without first ensuring you have correctly
identified the problem or disease and before you treat, and first take steps
to correct the cause of the problem.
9) The main cause of fish illness is STRESS.
Poor water quality, over crowding (too many fish), an incompatible mixture
of fish, too much water turbulence, disturbance, repeatedly netting them or
simply you poking about in the pond.
© FBAS 2004 RCM/RDE Pond Care Sheet 8 1/2